1/32nd of a radioactive element's atoms remain in a lunar rock sample. How many half lives old is the rock?

A. 1

B. 2

C. 3

D. 4

E. 5

Answers

Answer 1

Answer:

E. 5

Explanation:

N₀ = initial total number of radioactive elements number

N = Number of atoms of radioactive element after "n" half lives = N₀ /32

n = number of half lives

Number of atoms of radioactive element after "n" half lives is given as

[tex]N = N_{o}\left ( \frac{1}{2} \right )^{n}[/tex]

inserting the values

[tex]\frac{N_{0}}{32} = N_{o}\left ( \frac{1}{2} \right )^{n}[/tex]

[tex]\frac{1}{32} = \left ( \frac{1}{2} \right )^{n}[/tex]

n = 5


Related Questions

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.032.03 times a second. A tack is stuck in the tire at a distance of 0.357 m0.357 m from the rotation axis. Noting that for every rotation the tack travels one circumference, find the tack's tangential speed.

Answers

Final answer:

The tangential speed of the tack is 0.724 m/s, calculated using Vt = rω formula with the given values.

Explanation:

The tangential speed of the tack can be calculated using the formula:

Vt = rω

where Vt is the tangential speed, r is the distance from the rotation axis (0.357 m), and ω is the angular speed (2.03 times/s).

Substitute the values:

Vt = 0.357 m * 2.03 times/s = 0.724 m/s.

What potential difference would an electron have to fall through to acquire a speed of 3.00*10^6 m/sec?

Answers

Answer:

25.6 V

Explanation:

The kinetic energy of electron associated with its potential difference is given by eV which is equal to the 1/2 mv^2.

m = 9.1 x 10^-31 kg, v = 3 x 10^6 m/s, e = 1.6 x 10^-19 C

eV = 1/2 m v^2

V = mv^2 / 2 e

V = (9.1 x 10^-31) x (3 x 10^6)^2 / (2 x 1.6 x 10^-19)

V = 25.6 V

A single-slit diffraction pattern is formed on a distant screen. Assuming the angles involved are small, by what factor will the width of the central bright spot on the screen change if the distance from the slit to the screen is doubled?

Answers

Answer:

y and length is directly relation

Explanation:

Given data

A single-slit diffraction pattern is formed on a distant scree

angles involved = small

to find out

what factor will the width of the central bright spot on the screen change

solution

we know that  for single slit screen formula is

mass ƛ /area = sin θ and y/L = sinθ

so we can say mass ƛ /area =  y/L

and y = mass length  ƛ / area       .................1

in equation 1 here we can see y and length is directly relation so we can say from equation 1 that  the width of the central bright spot on the screen change if the distance from the slit to the screen is doubled

A long wire carries a current density proportional to the distance from its center, J=(Jo/ro)•r, where Jo and ro are constants appropriate units. Determine the magnetic field vector inside this wire.

Answers

Answer:

[tex]B = \mu_0(\frac{1}{3} \frac{J_0}{r_0} r^2)[/tex]

Explanation:

As the current density is given as

[tex]J = \frac{J_0}{r_0}r[/tex]

now we have current inside wire given as

[tex]i = \int J(2\pi r)dr[/tex]

[tex]i = \int \frac{J_0}{r_0} r(2\pi r)dr[/tex]

[tex]i = 2\pi \frac{J_0}{r_0} \int r^2 dr[/tex]

[tex]i = \frac{2}{3} \pi \frac{J_0}{r_0} r^3[/tex]

Now by Ampere's law we will have

[tex]\int B. dl = \mu_0 i[/tex]

[tex]B. (2\pi r) = \mu_0(\frac{2}{3} \pi \frac{J_0}{r_0} r^3)[/tex]

[tex]B = \mu_0(\frac{1}{3} \frac{J_0}{r_0} r^2)[/tex]

A train 400 m long is moving on a straight track with a speed of 81.4 km/h. The engineer applies the brakes at a crossing, and later the last car passes the crossing with a speed of 17.6 km/h. Assuming constant acceleration, determine how long the train blocked the crossing. Disregard the width of the crossing.

Answers

Answer:

86.5m

Explanation:

first convert km/h

then

81.4*1000/60*60=22.6

17.6*1000/60*60=4.89

then, x1/t1=x2/t2

we get

x2=400*4.89/22.6=86.5//

How would the solar system compare to the milky way if balls and marbles were used to scale their sizes

Answers

Answer:

explained below

Explanation:

solar system consist of sun, planets, asteroids, stars etc.

Milky Way is  a galaxy.

Combination of  many solar systems then forms galaxy.

Our solar system is a part of milky way galaxy.

If you consider marbles as planets and balls as stars.

so, we can say that in milky way is consist of 100-400 billions balls and 100 million marbles.

A ferromagnet and electromagnet can be used together to

(a) Create a strong magnetic field.
(b) Create a weak magnetic field.
(c) Cancel any external magnetic fields.

(d) Create a heavy magnet.

Answers

Answer:

The correct option is : (a) Create a strong magnetic field.

Explanation:

An electromagnet is a substance which produces magnetic field when electric current is passed through it. The magnetic field produced by them disappears when the electric current is turned off.

A Ferromagnetic substance is a substance that gets magnetized when kept in an external magnetic field. Such substances remain magnetized even after the external magnetic field is removed.

When an electromagnet and a ferromagnet is combined, it results in the production of a strong magnetic field.

A battery can be modeled as a source of emf in series with both a resistance of 10 Ω and an inductive reactance of 5 Ω. For a maximum power delivered to the load, the load should have a resistance of RL = 10 Ω, an inductive reactance of zero, and a capacitive reactance of 5 Ω. With this load, is the circuit in resonance?

Answers

Answer:

Yes circuit is in resonance

Explanation:

As we know that the circuit consist of a resistance of 10 ohm and an inductive reactance of 5 ohm

This circuit is connected to a load with having value of resistance of 10 ohm and capacitive reactance of 5 ohm

now they are all in series so as we know that capacitor and inductor is in opposite phase so here reactance of inductor is cancelled by the reactance of capacitor due to the opposite phase of them also they are same in magnitude

so we have

[tex]x_L = x_C[/tex]

so the circuit is purely resistive and hence we can say that it must be in resonance

he work function of a certain metal is 1.90 eV. What is the longest wavelength of light that can cause photoelectron emission from this metal? (1 eV = 1.60 × 10-19 J, c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ∙ s)

Answers

Answer:

6538.8 Angstrom

Explanation:

work function, w = 1.9 eV = 1.9 x 1.6 x 10^-19 J = 3.04 x 10^-19 J

Let the longest wavelength is λ.

W = h c / λ

λ = h c / W

λ = (6.626 x 10^-34 x 3 x 10^8) / (3.04 x 10^-19)

λ = 6.5388 x 10^-7 m = 6538.8 Angstrom

Thus, the longest wavelength is 6538.8 Angstrom.

A plane electromagnetic wave, with wavelength 6 m, travels in vacuum in the positive x direction with its electric vector E, of amplitude 214.6 V/M, directed along y axis. What is the frequency f of the wave? 250 MHz 100 MHz 50 MHz 105 MHz 25 MHz [2 points] (b) A plane electromagnetic wave, with wavelength 6 m, travels in vacuum in the positive x direction with its electric vector E, of amplitude 214.6 V/M, directed along y axis. What is the direction of the magnetic field associated with the wave? (i,j,k are the unit vectors corresponding to x, y and z directions) -j

Answers

a) For an EM wave traveling in a vacuum, this equation holds true:

c = fλ

c is the speed of light in a vacuum, f is the frequency, and λ is the wavelength.

Given values:

c = 3×10⁸m/s

λ = 6m

Plug in the values and solve for f:

3×10⁸ = f(6)

f = 50MHz

b) The direction of an EM wave's Poynting vector determines the direction of the wave's propagation.

S = 1/μ₀(E×B)

S is the Poynting vector, μ₀ is the magnetic constant, E is the electric field vector, and B is the magnetic field vector. Note that we are taking the cross product between E and B, not taking the product of two scalar quantities.

Since S depends on the cross product of E and B, you may use the right hand rule in the following way to determine the direction of B:

The EM wave travels in the +x direction, therefore S points in the +x direction. Face your palm in the +x direction.E points along the y axis. Let us arbitrarily choose +y. Point your thumb in the +y direction.This will constrain your other fingers to point in the +z direction. If you point your thumb in the -y direction then your fingers will point in the -z direction.

You can conclude that B must point along the z axis, so you can represent B with the k unit vector.

a) The frequency f of the wave is 50 MHz.

b) The direction of the magnetic field associated with the wave is along Z-axis with the k unit vector.

What is Poynting vector?

The Poynting vector is a measurement that expresses the strength and direction of the energy flow in electromagnetic waves.

Mathematically;

S = 1/μ₀(E×B)

Where: S =  Poynting vector,  μ₀ = magnetic constant, E = electric field vector, and B = the magnetic field vector

a) For an EM wave traveling in a vacuum, it can be written that:

c = fλ

Where c is the speed of light in a vacuum, f is the frequency, and λ is the wavelength.

Speed of light in vacuum: c = 3×10⁸m/s

Wavelength of the given EM Wave: λ = 6m

Hence, the frequency of the EM wave: f =  3×10⁸m/s/  6m = 50MHz.

b) The EM wave travels in the x direction, therefore S points in the x direction.

Electric field acts along the y axis.

Hence, The direction of the magnetic field associated with the wave is along Z-axis with the k unit vector.

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point) A tank in the shape of an inverted right circular cone has height 5 meters and radius 4 meters. It is filled with 4 meters of hot chocolate. Find the work required to empty the tank by pumping the hot chocolate over the top of the tank. The density of hot chocolate is δ=1080 kg/m3. Your answer must include the correct units.

Answers

Answer:

W = 907963.50 J = 907.96 J

Explanation:

Note: Refer to the figure attached

Now, from the figure we have similar triangles ΔAOB and ΔCOD

we have

[tex]\frac{5}{4}=\frac{x}{r}[/tex]

or

[tex]r=\frac{4x}{5}[/tex]

Now, the work done to empty the tank can be given as:

[tex]W = \int\limits^4_0 {(5-x)\rho\times g A} \, dx[/tex]

or

[tex]W = \int\limits^4_0 {(5-x)1080\times 9.8 (\pi r^2)} \, dx[/tex]

or

[tex]W = \int\limits^4_0 {(5-x)\times10584\times (\pi (\frac{4x}{5})^2)} \, dx[/tex]

or

[tex]W = 6773.76\pi\int\limits^4_0 {(5-x)x^2)} \, dx[/tex]

or

[tex]W = 6773.76\pi[\frac{5}{3}x^3-\frac{1}{4}x^4]^4_0 [/tex]

or

[tex]W = 6773.76\pi[\frac{128}{3}] [/tex]

or

W = 907963.50 J = 907.96 J

The work required to empty the tank by pumping the hot chocolate over the top of the tank is 907.96 J.

What is work done?

Work done is the force applied on a body to move it over a distance. The work required to lift a body through a height h is given as,

[tex]W=Fh[/tex]

Here, (F) is the magnitude of force and (f) is the height.

It can be rewritten as,

[tex]W=mgh[/tex]

Here, (m) is the mass of the body.

The tank is in the shape of an inverted right circular cone with height 5 meters and radius 4 meters. As, It is filled with 4 meters of hot chocolate.

Here the ratio of height to radius should be equal to the height at another point (say x), to the radius of that point. Thus,

[tex]\dfrac{5}{4}=\dfrac{x}{r}\\r=\dfrac{4x}{5}[/tex]

For the distance x the work done to empty the cone can be given as,

[tex]W=\int^4_0 (5-x)\rho g \pi r^2 dx\\W=\int^4_0 (5-x)1080\times9.81 \pi (\dfrac{4x}{5})^2 dx\\W=22280.4\int^4_0(5-x)x^2 dx\\W=22280.4[\dfrac{128}{3}]\\W=907.96\rm J[/tex]

Thus, the work required to empty the tank by pumping the hot chocolate over the top of the tank is 907.96 J.

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(b) If TH = 500°C, TC = 20°C, and Wcycle = 200 kJ, what are QH and QC, each in kJ?

Answers

Answer:

QC = 122 KJ

QH = 2.64 x 122 = 322 KJ

Explanation:

TH = 500 Degree C = 500 + 273 = 773 K

TC = 20 degree C = 20 + 273 = 293 K

W cycle = 200 KJ

Use the formula for the work done in a cycle

Wcycle = QH - QC

200 = QH - QC    ..... (1)

Usse

TH / TC = QH / QC

773 / 293 = QH / QC

QH / QC = 2.64

QH = 2.64 QC     Put it in equation (1)

200 = 2.64 QC - QC

QC = 122 KJ

So, QH = 2.64 x 122 = 322 KJ

In a Little League baseball game, the 145 g ball enters the strike zone with a speed of 17.0 m/s . The batter hits the ball, and it leaves his bat with a speed of 25.0 m/s in exactly the opposite direction. What is the magnitude of the impulse delivered by the bat to the ball? If the bat is in contact with the ball for 1.0 ms , what is the magnitude of the average force exerted by the bat on the ball?

Answers

Answer:

impulse = 6.09 kg m/s

Force = 6090 N

Explanation:

As we know that the impulse is defined as the change in momentum of the ball

so here we will have

[tex]\Delta P = mv_f - mv_i[/tex]

now we know that

[tex]v_f = 25 m/s[/tex]

initial speed is given as

[tex]v_i = -17 m/s[/tex]

now impulse is given as

[tex]\Delta P = 0.145(25 - (-17))[/tex]

[tex]\Delta P = 6.09 kg m/s[/tex]

Now we also know that average force is defined as the rate of change in momentum

[tex]F = \frac{\Delta P}{\Delta t}[/tex]

so we have

[tex]F = \frac{6.09}{1 \times 10^{-3}}[/tex]

[tex]F = 6.09 \times 10^3 N[/tex]

Final answer:

The magnitude of the impulse delivered by the bat to the ball is 6.09 kg*m/s. The magnitude of the average force exerted by the bat on the ball during a contact time of 1.0 ms is 6090 N.

Explanation:

The question relates to the concept of impulse and average force in a collision scenario. Impulse is given by the change in momentum of the object, and it can also be calculated as the average force (F) multiplied by the time duration (t) of the impact.

Considering the baseball scenario where the ball has a mass of 0.145 kg, enters the strike zone at 17.0 m/s and leaves in the opposite direction at a speed of 25.0 m/s, we can calculate the magnitude of the impulse delivered by the bat as follows:

Impulse (J) = Change in momentum = m(v_final - v_initial)J = 0.145 kg * (25.0 m/s - (-17.0 m/s))J = 0.145 kg * 42.0 m/sJ = 6.09 kg*m/s (This is the magnitude of the impulse)

To find the magnitude of the average force exerted by the bat on the ball, we use the time duration of the contact:

Average force (F) = Impulse (J) / Time duration (t)F = 6.09 kg*m/s / 0.001 sF = 6090 N

So, the magnitude of the average force exerted by the bat on the ball is 6090 N.

A 39000-Mg ocean liner has an initial velocity of 4 km/h. Neglecting the frictional resistance of the water, determine the time required to bring the liner to rest by using a single tugboat which exerts a constant force of 210 kN. (Round the final answer to the nearest whole number.)

Answers

Answer:

t = 206 sec

Explanation:

m = mass of the ocean liner = 39000 Mg = 39000 x 10⁶ g = 3.9 x 10⁷ kg

F = constant force applied by the tugboat = 210 kN = 210000 N

v₀ = initial velocity of the liner = 4 km/h = 1.11 m/s

v = final velocity of the liner = 0 m/s

a = acceleration of the liner

Acceleration of the liner is given as

[tex]a = - \frac{F}{m}[/tex]

[tex]a = - \frac{210000}{3.9\times 10^{7}}[/tex]

a = - 0.0054 m/s²

Using the equation

v = v₀ + at

0 = 1.11 + (- 0.0054) t

t = 206 sec

What is the intensity of a sound with a sound intensity level (SIL) 67 dB, in units of W/m^2?

Answers

Answer:

The intensity of sound (I) = 3.16 x 10⁻⁶ W/m²

Explanation:

We have expression for sound intensity level (SIL),

              [tex]L=10log_{10}\left ( \frac{I}{I_0}\right )[/tex]

Here we need to find the intensity of sound (I).

               [tex]L=10log_{10}\left ( \frac{I}{I_0}\right )\\\\log_{10}\left ( \frac{I}{I_0}\right )=0.1L\\\\\frac{I}{I_0}=10^{0.1L}\\\\I=I_010^{0.1L}[/tex]

Substituting

          L = 67 dB and I₀ = 10⁻¹² W/m² in the equation

          [tex]I=I_010^{0.1L}=10^{-12}\times 10^{0.1\times 65}\\\\I_0=10^{-12}\times 10^{6.5}=10^{-5.5}=3.16\times 10^{-6}W/m^2[/tex]

The intensity of sound (I) = 3.16 x 10⁻⁶ W/m²

If a ball is thrown vertically upward from the roof of a 32 foot tall building with a velocity of 48 ft/sec, its height in feet after T seconds is ______.

Answers

Answer:

The ball's maxium height after 1.49 seconds will be 103.52 feet.

Explanation:

Vi= 48 ft/sec

hi= 32 ft

hf= ?

time of maxium height :  

t= Vi/g    t= 48 ft/sec  /  32.17 ft/sec²

t= 1.49 sec

maxium height:

hf= hi + Vi * t

hf= 32ft + 48 ft/sec * 1.49 sec

hf= 103.52 ft

What is the fundamental frequency on a 8 m rope that is tied at both ends if the speed of the waves is 16 m/s?

Answers

Answer:

1 Hz

Explanation:

For rope fixed on both ends the length corresponds to λ/2  (λ is wavelength)\

 Thus L =  λ/2

=> λ = 16 m

We know that frequency and wavelength are related as

 f x λ = v   where f is frequency and v is speed of the wave

thus f = v/λ

        f = 16/16 =1 Hz

Final answer:

The fundamental frequency of an 8 m rope tied at both ends with waves traveling at a speed of 16 m/s is 1 Hz, calculated using the formula for the fundamental frequency of a standing wave.

Explanation:

The fundamental frequency of a string fixed at both ends (like an 8 m rope with waves traveling at 16 m/s) can be found using the formula for the fundamental frequency of a standing wave, which is given by f = v / (2L), where f is the fundamental frequency, v is the speed of the wave, and L is the length of the string. In this case, L = 8 m and v = 16 m/s. Plugging these values into the formula gives us:

f = 16 m/s / (2 × 8 m) = 1 Hz.

Therefore, the fundamental frequency of the 8 m rope tied at both ends with a wave speed of 16 m/s is 1 Hz.

A solenoid 3.0 cm long consists of 5748 loops of wire. If the magnetic field inside the solenoid is 1.0T. what is the magnitude of the current that flows through it? A) 52 A B) 0.24 A C) 4.2 A D) 3.0 A

Answers

C. I = 4.2A.

The magnetic field inside a solenoid is given by the equation:

B = μ₀NI/L

Clearing I for the equation above.

I = BL/μ₀N

With B = 1.0T, L = 3 x 10⁻²m, μ₀ = 4π x 10⁻⁷T.m/A and N = 5748turns

I = [(1.0T)(3 x 10⁻²m)]/[(4π x 10⁻⁷T.m/A)(5748turns)]

I = 4.15 ≅ 4.2A

A small charged sphere is attached to a thread and placed in an electric field. The other end of the thread is anchored so that when placed in the field the sphere is in a static situation (all the forces on the sphere cancel). If the thread is horizontal, find the magnitude and direction of the electric field. The sphere has a mass of 0.018 kg and contains a charge of + 6.80 x 103 C. The tension in the thread is 6.57 x 10-2 N. Show your work and/or explain your reasoning. (20 pts)

Answers

Answer:

[tex]E = 9.66\times 10^{-6} N/C[/tex]

direction is Horizontal

Explanation:

As we know that the string is horizontal here

so the tension force in the string is due to electrostatic force on it

now we will have

[tex]F = qE[/tex]

so here the force is tension force on it

[tex]F = 6.57 \times 10^{-2} N[/tex]

[tex] Q = 6.80 \times 10^3 C[/tex]

now we have

[tex]6.57 \times 10^{-2} = (6.80 \times 10^3)E[/tex]

[tex]E = 9.66\times 10^{-6} N/C[/tex]

direction is Horizontal

Final answer:

The magnitude of the electric field on the charged sphere in this scenario is approximately 1.17 x 10^-5 N/C. The direction of the electric field is horizontal, which is the same direction as the tension in the thread.

Explanation:

To start, we can use the equilibrium condition where the tension in the thread is equal to the force due to the electric field and gravity on the sphere. The formula to calculate the electric force is F = qE, and the gravitational force is F = mg, where F is the force, q is the electric charge, E is the electric field, m is the mass of the object, and g is the gravity constant.

Tension - electric force - gravitational force equals zero: T - F_electric - F_gravity = 0. We fill in the previous formulas: T - qE -mg = 0. This can be rearranged to E = (T + mg) / q.

In this case, the sphere's mass m is 0.018 kg, the tension T is 6.57 x 10^-2 N, and the sphere's charge q is 6.80 x 10^3 C, and we use g = 9.81 m/s². So, E = ((6.57 x 10^-2) + (0.018 * 9.81)) / 6.80 x 10^3.

This leads to an electric field magnitude of approximately 1.17 x 10^-5 N/C. The direction of the electric field is the same as the direction of the tension, which is horizontal due to the thread being horizontal.

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A 2.0-kg block is on a perfectly smooth (frictionless) ramp that makes an angle of 30^\circ30 ​∘ ​​ with the horizontal. What is the force of the ramp on the block?

Answers

Final answer:

The force of the ramp on the block is 2.45 N.

Explanation:

To find the force of the ramp on the block, we need to consider the forces acting on the block. The only force acting on the block along the ramp is the component of the weight of the block that is parallel to the ramp. This force can be calculated using the equation:

F = mg sin(theta)

where F is the force, m is the mass of the block, g is the acceleration due to gravity, and theta is the angle of the ramp. Plugging in the values, we get:

F = (2.0 kg)(9.8 m/s^2) sin(30 degrees) = 4.9 N sin(30 degrees) = 2.45 N

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A car of mass 2kg is moving with 6m/s when collides with a second car of mass 3kg which is coming from opposite direction with 2m/s. the two cars lock together and move along the road. What is the speed of the cars immediately after collision?
3m/s
0m/s
1.2m/s
2.5m/s


Answers

Answer:

Speed of the car after the collision is 1.2 m/s

Explanation:

It is given that,

Mass of first car, m₁ = 2 kg

Velocity of first car, v₁ = 6 m/s

Mass of second car, m₂ = 3 kg

Velocity of second car, v₂ = -2 m/s (it is travelling in opposite direction)

The two cars lock together and move along the road. This shows an inelastic collision. Let their common velocity is V. On applying the conservation of momentum as :

[tex]m_1v_1+m_2v_2=(m_1+m_2)V[/tex]

[tex]V=\dfrac{m_1v_1+m_2v_2}{(m_1+m_2)}[/tex]

[tex]V=\dfrac{2\ kg\times 6\ m/s+3\ kg\times (-2\ m/s)}{5\ kg}[/tex]

V = 1.2 m/s

So, after collision the speed of the cars is 1.2 m/s. Hence, this is the required solution.

Consider a cloudless day on which the sun shines down across the United States. If 2278 kJ2278 kJ of energy reaches a square meter (m2)(m2) of the United States in one hour, how much total solar energy reaches the entire United States per hour? The entire area of the United States is 9,158,960 km29,158,960 km2 .

Answers

Answer:

Total solar energy reaches the entire United States per hour is[tex]2.0864\times 10^{16} [/tex] kilo Joules.

Explanation:

Amount of energy reaching 1 square meter of area = 2278 kJ/hour

Total area of the United States = [tex]9,158,960 km^2=9,158,960\times 10^6 m^2[/tex]

[tex](1 km^2=10^6 m^2)[/tex]

Amount of energy reaching [tex]9,158,960\times 10^6 m^2[/tex] of area:

[tex]2278 kJ/hour\times 9,158,960\times 10^6 kJ/hour[/tex]

[tex]=2.0864\times 10^{16} kJ/Hour[/tex]

Total solar energy reaches the entire United States per hour is[tex]2.0864\times 10^{16} [/tex] kilo Joules.

Final answer:

The total solar energy that reaches the entire United States per hour is 20,866,319,680 MJ.

Explanation:

To calculate the total solar energy reaching the entire United States per hour, given that 2278 kJ of energy reaches a square meter in one hour, we would first convert the entire area of the United States into square meters. Since the area is given as 9,158,960 km², we convert this to square meters by multiplying by (1000 m/km)²:

9,158,960 km² * (1000 m/km)² = 9,158,960,000,000 m²

Next, we multiply the area in square meters by the energy received per square meter:

9,158,960,000,000 m² * 2278 kJ/m² = 20,866,319,680,000 kJ

To generate an accurate answer, we can express this in megajoules (MJ) by dividing by 1,000 (since 1 MJ = 1,000 kJ):

20,866,319,680,000 kJ / 1,000 = 20,866,319,680 MJ

Therefore, the total solar energy that reaches the entire United States per hour is 20,866,319,680 MJ.

A household refrigerator runs one-fourth of the time and removes heat from the food compartment at an average rate of 800 kJ/h. If the COP of the refrigerator is 2.2, determine the power the refrigerator draws when running.

Answers

Answer:

1454.54 kJ/h or 0.404 kW

Explanation:

Given:

Removal of heat by the refrigerator = 800 kJ/h

Coefficient of performance, COP of the refrigerator = 2.2

given that the  refrigerator runs one-fourth of the time only

therefore, refrigerator removes the heat, Q = [tex]4\times 800 kJ/h[/tex] = 3200 kJ/h

Now, the Power drawn by the refrigerator while running = [tex]\frac{Q}{COP}[/tex]

=  [tex]\frac{3200 kJ/h}{2.2}[/tex]

= 1454.54 kJ/h

Hence, the power drawn by the refrigerator while running is = 1454.54 kJ/h

or 0.404 kW      (as 1 kW = 3600 kJ/h)

Final answer:

To determine the power the refrigerator draws when running, use the formula for the coefficient of performance (COP) and substitute the given values

Explanation:

To determine the power the household refrigerator draws when running, we need to use the formula for the coefficient of performance (COP) of a refrigerator. The COP is given by the ratio of the heat removed from the cold reservoir to the work done on the engine's working substance. In this case, the COP is given as 2.2.

The power drawn by the refrigerator can be calculated using the formula:

Power = COP x Heat removed from the cold reservoir / Time

Given that the refrigerator runs one-fourth of the time and removes heat from the food compartment at an average rate of 800 kJ/h, we can substitute these values into the formula to find the power drawn by the refrigerator.

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At an instant when a soccer ball is in contact with the foot of the player kicking it, the horizontal or x component of the ball's acceleration is 900 m/s^2 and the vertical or y component of its acceleration is 870 m/s^2. The ball's mass is 0.31 kg. What is the magnitude of the net force acting on the soccer ball at this instant?

Answers

Answer:

390 N

Explanation:

The net acceleration is:

a² = aₓ² + aᵧ²

a² = (900 m/s²)² + (870 m/s²)²

a = 1250 m/s²

So the net force is:

F = ma

F = (0.31 kg) (1250 m/s²)

F = 390 N

A 1500-kg car traveling at 30 m/s east collides with a 3000-kg car traveling at 20 m/s south. The two cars stick together after the collision. What is the speed of the cars after collision?

Answers

Answer:

Speed of the cars after the collision is 3.34 m/s.

Explanation:

It is given that,

Mass of one car, m₁ = 1500 kg

Velocity of this car, v₁ = + 30 m/s ( in east )

Mass of other car, m₂ = 3000 kg

Velocity of other car, v₂ = - 20 m/s (in south)

The two cars stick together after the collision. It is a case of inelastic collision. Let v is the speed of cars after collision. It can be calculated using the conservation of linear momentum as :

[tex]m_1v_1+m_2v_2=(m_1+m_2)v[/tex]

[tex]v=\dfrac{m_1v_1+m_2v_2}{(m_1+m_2)}[/tex]

[tex]v=\dfrac{1500\ kg\times 30\ m/s+3000\ kg\times (-20\ m/s)}{1500\ kg+3000\ kg}[/tex]

v = -3.34 m/s

So, the speed of the cars after the collision is 3.34 m/s. Hence, this is the required solution.

Consider two planets in space that gravitationally attract each other if the mass of one of them stays the same and the mass of the other is doubled AND the distance between them is doubled, then the force between them changes by what factor? A. Doubled
B. Quadrupled
C. Tripled
D. Half as much

Answers

Answer:

D. half as much

Explanation:

let m and M be the mass of the planets and r be the distance between them.

then: the force of attraction between them is given by,

F = G×m×M/(r^2)

if we keep one mass constant and double the other and also double the distance between them.

the force of attraction becomes:

F1 = 2G×m×M/[(2×r)^2]

   = 2G×m×M/[4×(r)^2]

   = (1/2)G×m×M/(r^2)

   = 1/2×F

therefore, when you double one mass and keep the other mass constant and double the distance between the masses you decrease the force by a factor of 1/2.

What will an object weigh on the Moon's surface if it weighs 100 N on Earth's surface? (b) How many Earth radii must this same object be from the center of Earth if it is to weigh the same as it does on the Moon?

Answers

Answer:

Part a)

W = 16.7 N

Part b)

r = 2.45 R

Explanation:

Part a)

As we know that acceleration due to gravity on the surface of moon is 1/6 times the gravity on the surface of earth

So the force due to gravity will decrease by the factor of 6

so we will have

[tex]W_{moon} = \frac{1}{6}W_{earth}[/tex]

[tex]W_{moon} = \frac{1}{6}(100)[/tex]

[tex]W_{moon} = 16.7 N[/tex]

Part b)

For the same value of the weight as the surface of moon the acceleration due to gravity of earth must be 1/6 times

so we have

[tex]\frac{GM}{r^2} = \frac{GM}{6R^2}[/tex]

[tex]r^2 = 6R^2[/tex]

[tex]r = 2.45 R[/tex]

The object must be [tex]\( \sqrt{6} \)[/tex]  Earth radii from the center of Earth to weigh the same as it does on the Moon.

The weight of an object on the Moon's surface is approximately 1/6 of its weight on Earth's surface due to the Moon's lower gravitational acceleration. Therefore, the object that weighs 100 N on Earth will weigh:

[tex]\[ W_{\text{Moon}} = \frac{1}{6} \times W_{\text{Earth}} = \frac{1}{6} \times 100 \text{ N} = 16.67 \text{ N} \][/tex]

For the second part of the question, we need to find the Earth radius multiple where the gravitational acceleration is the same as that of the Moon. The gravitational acceleration g on Earth is approximately [tex]\( 9.81 \, \text{m/s}^2 \)[/tex], and on the Moon, it is [tex]\( \frac{9.81}{6} \, \text{m/s}^2 \)[/tex]. The gravitational acceleration ( g' ) at a distance r from the center of Earth is given by:

[tex]\[ g' = g \left( \frac{R_{\text{Earth}}}{r} \right)^2 \][/tex]

where [tex]\( R_{\text{Earth}} \)[/tex] is the radius of Earth. We want to find r such that ( g' ) is equal to the gravitational acceleration on the Moon:

[tex]\[ g \left( \frac{R_{\text{Earth}}}{r} \right)^2 = \frac{g}{6} \][/tex]

Solving for r:

[tex]\[ \left( \frac{R_{\text{Earth}}}{r} \right)^2 = \frac{1}{6} \] \[ \frac{R_{\text{Earth}}}{r} = \sqrt{\frac{1}{6}} \] \[ r = R_{\text{Earth}} \sqrt{6} \][/tex]

A 10.2-kg mass is located at the origin, and a 4.6-kg mass is located at x = 8.1 cm. Assuming g is constant, what is the location of the center of mass xcom and the location of the center of gravity xcogof the two masses? Are the locations the same? Why or why not?

Answers

Answer:

center of mass of the two masses will lie at x = 2.52 cm

center of gravity of the two masses will lie at x = 2.52 cm

So center of mass is same as center of gravity because value of gravity is constant here

Explanation:

Position of centre of mass is given as

[tex]r_{cm} = \frac{m_1r_1 + m_2r_2}{m_1 + m_2}[/tex]

here we have

[tex]m_1 = 10.2 kg[/tex]

[tex]m_2 = 4.6 kg[/tex]

[tex]r_1 = (0, 0)[/tex]

[tex]r_2 = (8.1cm, 0)[/tex]

now we have

[tex]r_{cm} = \frac{10.2 (0,0) + 4.6 (8.1 , 0)}{10.2 + 4.6}[/tex]

[tex]r_{cm} = {(37.26, 0)}{14.8}[/tex]

[tex]r_{cm} = (2.52 cm, 0)[/tex]

so center of mass of the two masses will lie at x = 2.52 cm

now for center of gravity we can use

[tex]r_g_{cm} = \frac{m_1gr_1 + m_2gr_2}{m_1g + m_2g}[/tex]

here we have

[tex]m_1 = 10.2 kg[/tex]

[tex]m_2 = 4.6 kg[/tex]

[tex]r_1 = (0, 0)[/tex]

[tex]r_2 = (8.1cm, 0)[/tex]

now we have

[tex]r_g_{cm} = \frac{10.2(9.8) (0,0) + 4.6(9.8) (8.1 , 0)}{10.2(9.8) + 4.6(9.8)}[/tex]

[tex]r_g_{cm} = {(37.26, 0)}{14.8}[/tex]

[tex]r_g_{cm} = (2.52 cm, 0)[/tex]

So center of mass is same as center of gravity because value of gravity is constant here

Final answer:

The center of mass and center of gravity for the two given masses are both located at x = 2.49 cm from the origin. In typical situations where gravitational forces are uniform, the center of gravity will coincide with the center of mass.

Explanation:

The location of the center of mass (xcom) and the center of gravity (xcog) for two bodies or particles can be calculated using the following formula: xcom = m1x1 + m2x2 / (m1 + m2) where m1, m2 are the masses and x1, x2 are their respective positions. In this case, m1 = 10.2 kg, x1 = 0 cm (since it's at the origin), m2 = 4.6 kg, and x2 = 8.1 cm.

Using these values, the formula becomes xcom = (10.2 kg * 0 cm + 4.6 kg * 8.1 cm) / (10.2 kg + 4.6 kg) = 36.86 cm / 14.8 kg = 2.49 cm. So, the center of mass is at x = 2.49 cm from the origin.

The concept of center of gravity is a specific application of the center of mass in the presence of a gravitational field. In everyday circumstances, where gravitational forces are uniform, the center of gravity coincides with the center of mass. Therefore, for this case, the center of gravity (xcog) will also be at x = 2.49 cm from the origin.

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A 2-kg mass attached to a spring that is compressed 40 cm has a maximum velocity of 10 m/s. If the spring is then compressed by 50 cm, what is the speed when the spring is at half its amplitude?

Answers

Answer:

10.83 m/s

Explanation:

Case 1:

m = mass attached to spring = 2 kg

x = compression of the spring = 40 cm = 0.40 m

k = spring constant

v₀ = maximum speed = 10 m/s

Using conservation of energy

maximum spring potential energy = maximum kinetic energy

(0.5) k x² = (0.5) m v₀²

k (0.40)² = (2) (10)²

k = 1250 N/m

Case 2 :

m = mass attached to spring = 2 kg

A = amplitude = 50 cm = 0.50 m

x = compression of the spring at half amplitude = A/2 = 50/2 = 25 cm = 0.25 m

k = spring constant = 1250 N/m

v = speed = ?

Using conservation of energy

maximum spring potential energy = spring potential energy + kinetic energy

(0.5) k A² = (0.5) k x² + (0.5) m v²

(1250) (0.50)² = (1250) (0.25)² + (2) v²

v = 10.83 m/s

A soccer ball with mass 0.420 kg is initially moving with speed 2.00 m/s. A soccer player kicks the ball, exerting a constant force of magnitude 40.0 N in the same direction as the ball’s motion. Over what distance must the player’s foot be in contact with the ball to increase the ball’s speed to 6.00 m/s?

Answers

Final answer:

The player's foot must be in contact with the ball for a distance of 1.48 meters to increase the ball's speed from 2.00 m/s to 6.00 m/s.

Explanation:

To increase the ball's speed from 2.00 m/s to 6.00 m/s, we can use the equation:

v^2 = u^2 + 2as

where v is the final velocity (6.00 m/s), u is the initial velocity (2.00 m/s), a is the acceleration, and s is the distance.

Rearranging the equation, we have:

s = (v^2 - u^2) / (2a)

Plugging in the values, we get:

s = (6.00^2 - 2.00^2) / (2 * 40.0)

s = 1.48 m

Therefore, the player's foot must be in contact with the ball for a distance of 1.48 meters.

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Final answer:

The physics concepts of force, mass, acceleration, and work were used to determine the distance over which the soccer player's foot needs to be in contact with the soccer ball in order to increase its speed from 2.00 m/s to 6.00 m/s. The resulting distance was approximately 0.09 m or 9 cm.

Explanation:

This question involves the relationship between force, mass, and acceleration, as well as the concept of work. Great! For the student to understand this, we need to look at a couple of formulas from physics. The force exerted on an object equals its mass times its acceleration (F = ma). Also, work done on an object is the force applied to it times the distance over which the force is applied (W = Fd).

Firstly, we need to determine the acceleration of the soccer ball when it is kicked. Using the first formula, we rearrange to find a = F/m. Here, F is the force applied (40.0 N) and m is the mass of the soccer ball (0.42 kg). Substituting these values, we get a = 40.0N / 0.42kg = approximately 95.2 m/s².

The initial speed of the ball is 2.00 m/s and the final speed we want is 6.00 m/s. The change in speed (which is also the change in velocity, as the direction doesn't change) is therefore 6.00 m/s - 2.00 m/s = 4.00 m/s. Using the formula for acceleration, which is a change in velocity divided by time (a = Δv / t), we can plug in our known values to solve for the time of contact: t = Δv / a = 4.00 m/s / 95.2 m/s² = approximately 0.042 s.

With the time of contact known, we can now determine the distance over which the soccer player's foot must be in contact with the ball using the formula for distance traveled during uniformly accelerated motion: d = vt + 0.5at². The initial velocity v is 2.00 m/s, the time of contact t is 0.042 s, and the acceleration a is 95.2 m/s². Substituting these values, we find that the distance is approximately 0.09 m or 9 cm.

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