The Sears Tower is nearly 400 m high. How long would it take a steel ball to reach the ground if dropped on the top? What will be it’s velocity the moment for it touches the ground?

Answer:

Option D: 21.8 degrees

Explanation:

In a parallel RL circuit, the current in the resistor R and that in the inductor L are separated among themselves 90 degrees as illustrated in the attached image. In the image the current in the resistor is represented in orange, that of the inductor in blue, and the total current (vector addition of the previous two) is represented  in red, forming a certain angle (theta) with respect to the current in the resistor. The output voltage is the same as the input voltage as measured over the resistor R.

Therefore, the phase angle that separated output voltage and total current can be obtained using the fact that tan(phase angle) = [tex]\frac{I_l}{I_R} = \frac{x}{y} \frac{4}{10}[/tex], therefore the angle is the arctangent of 4/10:

[tex]arctang(\frac{4}{10} )= 21.801[/tex] degrees.

Answer:

The phase angle between voltage and current in a parallel [tex]RL[/tex] circuit is 21.8°

Explanation:

In this question  input voltage [tex]V_i_n[/tex]  across both the components, the resistor and inductor is same since it is  a  parallel [tex]RL[/tex] circuit.  

Current cross resistor [tex]I_R=10 mA[/tex]

Current across inductor [tex]I_L=2 mA[/tex]  

Inductive reactance [tex]X_L= \frac{ V_i_n}{I_L} = \frac{V_i_n}{(2 mA)}[/tex]

Resistance of the resistor [tex]R= \frac{V_i_n}{I_R} = \frac {V_i_n}{(10 mA)}[/tex][tex][/tex]

Phase angle between voltage and current ∅ [tex] =tan^-^1 R/X_L[/tex]

[tex]=tan^-^1 \frac{(V_i_n /10)}{(V_i_n /2)}=  tan^-^1 \ \frac{2}{10}=tan^-^1\ 0.4[/tex]

=21.8°

Answer:

Avoidance-Avoidance

Explanation:

You don't want either, but you have to pick one.  

Final answer:

The type of conflict that you would likely experience when having to choose between being unemployed and accepting a job you do not like is called an intrapersonal conflict.

Explanation:

The type of conflict that you would likely experience when having to choose between being unemployed and accepting a job you do not like is called an intrapersonal conflict. This type of conflict occurs within an individual when they have conflicting desires or goals. In this case, you may have the desire to be employed and financially stable, but also the desire to find a job that you enjoy and are passionate about.

Answer:

Diffusion is net movement of anything from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in concentration. The concept of diffusion is widely used in many fields, including physics, chemistry, biology, sociology, economics, and finance.

Explanation:

Diffusion is the passive transport of molecules from an area of higher concentration to an area of lower concentration until the same concentration is reached throughout a space. Only molecules that are soluble in the medium and can cross barriers will diffuse. Variations on diffusion include the processes of filtration and osmosis.

Diffusion is a process by which molecules disperse in space in response to differences in concentration. It is a passive transport process, requiring no energy, occurring naturally in various situations such as the dispersal of a sample of gas in a closed container. Molecules move from areas of higher concentration to areas of lower concentration until equilibrium is reached where concentrations are equal throughout.

A principle of diffusion is that only substances which are soluble and can cross the membrane will diffuse through it. This is seen, for example, in the process of osmosis, which is the diffusion of water through a concentration gradient in living systems.

Importantly, in living organisms, the rate of diffusion must match the rate of oxygen uptake and carbon dioxide removal for the process to work effectively.

There are variations to this process, such as filtration and facilitated transport, which also move substances in response to a concentration gradient but may be enhanced by other factors such as pressure.

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Melting tin and then cooling it into a mold is an example of reversible physical changes.

Explanation:

         When an object undergoes a change in size, state, or shape and not in their chemical compositions referred to as physical change. But chemical change occurs as a result of the change in substances composition. It also forms a new one by the combination/ breakage of one or more objects.

         In the case of making gold cube into two pieces, there is no possibility of getting the original state again even the physical change happens. Match burning and relighting and sodium plus chlorine forming table salt show chemical change. But in tin melting and cooling it to form mold is the physical change i.e changes in state(liquid to solid) and are reversible too.

Answer:

yes, melting tin and then cooling it into a mold

Explanation:

Which would show an example of how physical changes are reversible?

cutting a gold bar in two pieces and then putting the pieces next to each other

burning a match and then relighting it

melting tin and then cooling it into a mold

combining sodium and chlorine to make the new material of table salt

Answer:

1732.05 J

Explanation:

The man is doing 100N of force on the rope at an angle of 30° where he is pulling a box 20 meters across the floor.

Work is equal to the force exerted in the direction of motion multiplied by the distance.

Mathematically, Work=F×D×CosineФ

where F=force in newtons

D=displacement in meters

Ф=the angle between the force vector and the direction of motion

Substitute values in formula

Work=100×20×cosine 30°

Work=100×20×0.86602540378

Work=1732.05 J

Answer:

C  1.67 × 10-9 N

Explanation:

The magnitude of the gravitational force between two objects is given by:

[tex]F=G\frac{m_1 m_2}{r^2}[/tex]

where

G is the gravitational constant

m1 ,m2 are the masses of the two objects

r is their separation

In this problem, we have:

[tex]m_1 = m_2 = 15.0 kg[/tex]

r = 3.00 m

Substituting into the equation, we find

[tex]F=(6.67\cdot 10^{-11}) \frac{(15)(15)}{3.00^2}=1.67\cdot 10^{-9} N[/tex]

The gravitational force between two 15.0 kg spheres separated by 3.00 meters is calculated to be approximately 1.67 × 10⁻⁹ N. Therefore, the correct answer is option C.

Newton's Law of Universal Gravitation:

where,

Plugging in the given values:

After simplifying:

Thus, the correct answer is C (1.67 × 10⁻⁹ N).

Answer: [tex]5 \frac{g}{cm^{3}}[/tex]

Explanation:

The density [tex]\rho[/tex] of a material is given by:

[tex]\rho=\frac{m}{V}[/tex] (1)

Where:

[tex]m=3645 g[/tex] is the mass of the cube

[tex]V[/tex] is the volume of the cube

Now, the volume of a cube is equal to the length [tex]L[/tex] of its edge to the power of 3:

[tex]V=L^{3}[/tex] (2)

If we know [tex]L=9 cm[/tex], the volume of this cube is:

[tex]V=(9 cm)^{3}=729 cm^{3}[/tex] (3)

Substituting (3) in (1):

[tex]\rho=\frac{3645 g}{729 cm^{3}}[/tex] (4)

[tex]\rho=5 \frac{g}{cm^{3}}[/tex] This is the density of the cube

Answer:

2. Understand nature

Explanation:

The main goal of science is to understand nature, because you need to find the best explanations for how nature works.

Answer:

a=12

Explanation:

- add 13 to both sides

3/2a = 5+13

- multiply by 2/3

2/3 * 3/2 * a = 2/3 * 18

a = 12

Answer:

[tex]-30m/s^{2}[/tex]

Explanation:

The first equation of motion given as,

v = u +at

Here, u is initial and v is final velocity and a is acceleration and t is time taken.

As per question car initial velocity, u = 90 m/s, final velocity, v =0 and time taken, t = 3.00 s.

Substituting these values in first equation of motion, we get

   0 = 90 m/s + a×3.00 s

or, [tex]a = \frac{-90m/s}{3.00s}[/tex]

            [tex]a=-30m/s^{2}[/tex]

Thus, the deacceleration of the car is [tex]-30m/s^{2}[/tex]

The acceleration of the car that goes from 90.0 m/s to a stop in 3.00s is -30.0 m/s².

The acceleration of the car can be calculated by using the equation:

Acceleratin = (final velocity - initial velocity) / time

= (0-90)/3

= -30.0 m/s².

Answer:

9000 m

Explanation:

To calculate the distance traveled by cyclist, using the relation between distance, velocity and time as

d = v × t

Here, d is distance traveled, v is velocity and t is time taken.

We have, v = 30 m/s and t = 5 min = 5×60= 300 s.

Substituting these values in above formula we get

d = 30 m/s × 300 s

d = 9000 m.

Thus, the distance traveled by cyclist is 9000 m.

Answers:

a) 10 m

b) time=1.6 s, frquency=0.625 Hz

c) 6.25 m/s

Explanation:

a) If there is a crest at each dock and another three crests between the two docks, and the wavelength [tex]\lambda[/tex] is the distance between to crests; this means we have [tex]4\lambda[/tex] in [tex]40 m[/tex]:

[tex]40 m=4\lambda[/tex]

Clearing [tex]\lambda[/tex]:

[tex]\lambda=\frac{40 m}{4}[/tex]

[tex]\lambda=10 m[/tex]

b) This part can be solved by a Rule of Three:

If 10 waves ---- 16 s

1 wave ----- [tex]T[/tex]

Then:

[tex]T=\frac{(1 wave)(16 s)}{10 waves}[/tex]

[tex]T=1.6 s[/tex] This is the period of the wave

On the other hand, the frequency [tex]f[/tex] of the wave has an inverse relation with its period [tex]T[/tex]:

[tex]f=\frac{1}{T}[/tex]

[tex]f=\frac{1}{1.6 s}[/tex]

[tex]f=0.625 Hz[/tex] This is the frequency of the wave

c) The speed [tex]v[/tex] of a wave is given by the following equation:

[tex]v=\frac{\lambda}{T}[/tex]

[tex]v=\frac{10 m}{1.6 s}[/tex]

Finally:

[tex]v=6.25 m/s[/tex]

Answer:

A waffle iron heated by coils

Explanation:

A waffle iron heated by coils - conduction

Food heated in a microwave oven - radiation

Pavement heated by the sun - radiation

A room heated by moving air - convection

Answer:

60 km an hour. If you travel 10 miles in 10 mins there are 60 minutes in an hour so your traveling 60 miles an hour

Explanation:

The speed of the truck is 16.67 m/s

To calculate the speed of the truck, we can use the following formula:

speed = distance ÷ time

In SI notation, we denote speed in meters per second.

So, we convert 10 km to meters (1 km = 1000 m)

⇒ (10 × 1000) m = 10000 m

Now, we convert 10 minutes to seconds (1 minute = 60 seconds)

⇒ (10 × 60) s = 600 s

∴ speed = 10000 m ÷ 600 s = 16.67 m/s

Answer:

Greatest ~ Corn Syrup, Seawater, Water, Oil, Gasoline ~ Least

Explanation:

Density (g/mL)

Corn Syrup: 1.4 g/mL

Seawater: 1.029 g/mL

Water: 0.997 g/mL

Oil: 0.93 g/mL

Gasoline: 0.7489 g/mL

We have that for a list from densest to least dense we have

From the question we are told

list these liquids from densest to least dense:

Generally

Density

This is simply defined as the ratio of mass to volume of a material or substance

Therefore

For a list from densest to least dense we have

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Answer:

All of the above

Explanation:

Scientific theories are explanations of various well known facts. They are hypotheses that best explain a scientific phenomenon. More development of theories doesn’t make it acceptable.  

Instead they have to supported by the results of  several tests performed by employing proper scientific methods. It is only after several years of thorough scientific research a theory is accepted as the best explanation of a phenomenon. Unlike facts that are accepted as universal truths theories can be proven wrong over time .

Answer:

all of the above

Explanation:

Explanation:

physical and chemical properties. Examples of physical properties are: color, smell, freezing point, boiling point, melting point, infra-red spectrum, attraction (paramagnetic) or repulsion (diamagnetic) to magnets, opacity, viscosity and density. There are many more examples.

The statement that best describes gravitational force is as follows:

Thus, the correct option for this question is A.

Gravitational force may be defined as a phenomenon that involves the force of attraction that occurs between objects that have significant masses in the universe, especially the attraction of the earth's mass to bodies near its surface.

This specific type of force is always applied to objects that have mass. This force generally works by attracting the mass object towards its surface. It is a type of universal attractive force which is directly proportional to the product of the masses of two bodies.

But still it is considered as the weakest force that significantly operating in the nature.

Therefore, the correct option for this question is A.

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Answer: C. both visible and invisible

Explanation:

Stars not only emit light in the visible range of the electromagnetic spectrum (what our eyes can see), they also emit light that is "invisible" to our eyes, because we do not have the receptors to perceive those frequencies.

In this sense, among this invisible range is ultraviolet light and infrared, for example.

Therefore, among the proposed options, the correct one is C:

Both visible and invisible

Answer:

Molecules are made up of atoms that are held together by chemical bonds. These bonds form as a result of the sharing or exchange of electrons among atoms. The atoms of certain elements readily bond with other atoms to form molecules. Examples of such elements are oxygen and chlorine.

Explanation:

A molecule forms from electrons shared between two atoms. The correct option is B.

Atoms join forces and engage in interaction to create molecules. To achieve a stable electron configuration, this frequently entails sharing electrons between atoms.

Covalent bonds, a sort of chemical bond, are made possible by this sharing of electrons.

The exchange of electrons between two atoms at their outermost energy levels, or valence shells, results in covalent bonds.

Atoms can acquire a more stable structure and fill their outermost energy levels by sharing electrons, just like the noble gases do.

The atoms can achieve a lower overall energy state thanks to this electron sharing, which makes the molecule more stable than the sum of its parts.

Thus, the correct option is B.

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Answer:

Orbit around the nucleus at specific energy levels

Explanation:

In the quantum model of the atom (Bohr's model), electrons orbit the nucleus at specific orbits corresponding to specific energy level - this means that an electron cannot be found in the space between two orbits.

Since each orbit correspond to a a precise energy level, this means that the spectrum of emission and absorption of an atom is discrete. In fact:

- When an electron jumps from a lower energy level to a higher energy level, it absorbs a photon whose energy is equal to the difference in energy between the two levels - so photons of only specific frequencies are absorbed

- When an electron jumps from a higher energy level to a lower energy level, it emits a photon whose energy is equal to the difference in energy between the two levels - so photons of only specific frequencies are emitted

Answer:

Most likely the Savanna or Desert.

Explanation:

Answer:

Explanation:

Rachel and her family is most suppose to be living in a desert area.

The forest and vegetation of a desert is similar to what described location of Rachel family. The region has Cacti, short grasses and small bushes flourish.

These natural vegetation is grown in desert as they do not need much water for there growth.

Answer:

The time the ball it takes to have the downward speed 4 m/s is 1.22 sec.

Explanation:

Lets explain the motion of the ball

The ball is kicked straight upwards with an initial vertical speed of 8.0 m/s

Its velocity decreases util it reaches the maximum height

At the maximum height its velocity is equal to zero

Then it fall down to the ground

We can ignore air resistance

Lets find the time it takes the ball to reach the maximum height

The acceleration of gravity is -9.8 m/s²

The initial velocity is 8 m/s upward

The final velocity is zero

So lets use the rule v = u + gt, where v is the final velocity, u is the initial

velocity, g is the acceleration of gravity and t is the time

u = 8 , v = 0 , g = -9.8

Substitute these value in the equation above

0 = 8 - 9.8 t

Add 9.8 t for both sides

9.8 t = 8

Divide both sides by 9.8

t = 40/49 seconds

The ball falls withe initial velocity zero and increases to reach 4 m/s

The velocity 4 m/s is downward

The acceleration of gravity is 9.8 m/s²

By using the same rule

u = 0 , v = 4 , g = 9.8

4 = 0 + 9.8 t

4 = 9.8 t

Divide both sides by 9.8

t = 20/49

The time the ball it takes to have the downward speed 4 m/s is the sum

of the two times above

The time the ball it takes = [tex]\frac{40}{49}+\frac{20}{49}=\frac{60}{49}=1.22[/tex] seconds

The time the ball it takes to have the downward speed 4 m/s is 1.22 sec.

Explanation:

Given:

x₀ = 0 m

v₀ = 4.2 m/s

t = 11.6 s

a = 2.3 m/s²

Find: x

x = x₀ + v₀ t + ½ at²

x = 0 m + (4.2 m/s) (11.6 s) + ½ (2.3 m/s²) (11.6 s)²

x ≈ 203 m

Round as needed.

Answer:

Weight of the suitcase, W = 220.5 N

Explanation:

It is given that,

Mass of the suitcase, m = 22.5 kg

Let W is the weight of the suitcase. The weight of an object is equal to the force acting on it due to the gravity. It is given by the product of mass and acceleration due to gravity.Mathematically, it is given by :

W = mg

[tex]W=22.5\times 9.8[/tex]

W = 220.5 N          

So, the weight of the suitcase is 220.5 N. Hence, this is the required solution.              

The weight of the suitcase is 220.5 Newton.

Given the following data:

We know that acceleration due to gravity (a) for an object is equal to 9.8 meter per seconds square.

To find how much this suitcase weigh, we would determine the weight of the suitcase by using the value of its mass.

Mathematically, the weight of an object is calculated by using the formula;

[tex]Weight = mg[/tex]

Where:

Substituting the values into the formula, we have;

[tex]Weight = 22.5[/tex] × [tex]9.8[/tex]

Weight = 220.5 Newton.

Therefore, the weight of the suitcase is 220.5 Newton.

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Answer:

Explanation:

a=v-u/t

v=final velocity

u=initial velocity

u=0(when a body starts from rest the initial velocity is 0)

v=100m/s

t=8s

a=100-0/8

=12.5m/s²

Answer:

The distance covered by the rocket after fuel ran out is [tex]3442.04 m[/tex]

Explanation:

Given that the rocket moves with an acceleration [tex]a=30m/s^2[/tex]

time [tex]t=5 s[/tex]

Since the rocket starts from rest initial velocity  [tex]u=0 s[/tex]

The distance it travelled within this time is given by  [tex]s=ut+ \frac{1}{2} at^2[/tex]                                                                                                  [tex]=0 \times 5+ \frac{1}{2} (30\times25)=375 m[/tex]

Velocity at this point is given by [tex]v=u+at[/tex]

[tex]v=0+30\times5=150m/s[/tex]

Given that at this height it runs out of fuel but travels further. Here final velocity [tex]v=0[/tex](maximum height), initial velocity[tex]u=150 m/s[/tex]  and time to zero velocity [tex]t=\frac{v}{g} = \frac{150}{9.8} =15.3 s.[/tex]

Thus it travels [tex]15.3 seconds[/tex] more after fuel running out. The distance covered during this period is given

[tex]s= ut+\frac{1}{2} gt^2=150 \times 15.3+1/2 \times9.8 \times 15.3^2=3442.04 m[/tex]

Answer:

C. 125

Explanation:

Given:

y₀ = h m

v₀ = 0 m/s

a = -10 m/s²

@ t − 1, y = 9/25 h m

@ t, y = 0 m

Find: h

Use constant acceleration equation:

y = y₀ + v₀ t + ½ at²

@ t:

0 = h + (0) (t) + ½ (-10) t²

0 = h − 5 t²

h = 5 t²

@ t − 1:

9/25 h = h + (0) (t − 1) + ½ (-10) (t − 1)²

9/25 h = h − 5 (t − 1)²

9/25 h = h − 5 (t² − 2t + 1)

9/25 h = h − 5 t² + 10 t − 5

0 = 16/25 h − 5 t² + 10 t − 5

Substitute:

0 = 16/25 (5 t²) − 5 t² + 10 t − 5

0 = 16/25 t² − t² + 2 t − 1

0 = -9/25 t² + 2 t − 1

0 = 9 t² − 50 t + 25

0 = (t − 5) (9t − 5)

t = 5/9 or 5

Since t > 1, t = 5.

Solving for h:

h = 5 t²

h = 125

Answer:

velocity is 5m/s

Explanation:

data

d=10m

t=2sec

v=?

from

v=d/t

v=10m/2s

v=5m/s

Its SPEED is (10m/2s) = 5 m/s .

It's not possible to determine its velocity from the given information, because we don't know the direction in which it rolled.