Why are objects that fall near Earth’s surface rarely in free fall?

Gravity does not act on objects near Earth’s surface.
Air exerts forces on falling objects near Earth’s surface.
The objects do not reach terminal velocity.
The objects can be pushed upward by gravity.

Answer:

1. 3) urges them to remember their duty and 2. 1) a model of loyalty are the correct answers.

Explanation:

In the first question, Wiglaf tries to convince his mates not to give up and to help his lord and also remembering what their intention was. Beowulf is supposed to receive help because he is old and he cannot deal with the monster by himself anymore, so Wiglaf is there because of that.

In the second one, it is seen that Wiglaf is the only one who doesn't give up on Beowulf, even when Beowulf is about to die after the fight with the dragon and Wiglaf kills it as a maximum expression of his loyalty.

The direction of motion of the cars after collision will be south of east. This is determined by the conservation of momentum, with the direction being the sum of the momenta of the two cars, taking into account their initial velocity and mass.

This question involves the conservation of momentum, a key concept in physics. Since the two cars stick together after the collision, the direction of their motion is the sum of their momenta, taking into account their mass and initial velocity.

First, convert the speeds from km/h to m/s. The 1500-kg car was travelling at 25 m/s towards the east (90 km/h) and the 3000-kg car was travelling at 16.67 m/s towards the south (60 km/h).

Momentum (p) is mass (m) times velocity (v), so the momentum of the first car is 1500 kg * 25 m/s = 37500 kg*m/s and the second car's momentum is 3000 kg * 16.67 m/s = 50000 kg*m/s. Since they stick together after the collision, the total momentum must remain the same. However, the momentum now has two components, one towards the east and the other towards the south. The magnitude of the resultant velocity is found using Pythagoras' theorem, sqrt[(37500 kg*m/s)^2 + (50000 kg*m/s)^2], and the direction is given by the arctangent of the ratio of the two components. Therefore, the direction of the cars will be south of east.

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The two cars will move together after the collision with a velocity of approximately 13.89 m/s at an angle of 53.12° south of east. This result is derived by applying the principle of conservation of momentum. We found the momentum components in the eastward and southward directions and used them to determine the direction and magnitude of the combined velocity.

This is a classic example of an inelastic collision where two objects stick together after collision. We use the conservation of momentum to find the direction of motion after the collision.

First, let's convert velocities to meters per second (m/s):

1500-kg car: 90 km/h = 25 m/s

3000-kg car: 60 km/h = 16.67 m/s

Next, we calculate the momentum of each car:

Eastward momentum of the 1500-kg car:

1500 kg * 25 m/s = 37500 kg·m/s

Southward momentum of the 3000-kg car:

3000 kg * 16.67 m/s = 50010 kg·m/s

Since the cars stick together after the collision, their combined mass is 1500 kg + 3000 kg = 4500 kg.

To find the velocity components of the combined mass after the collision:

Eastward velocity component:

(37500 kg·m/s) / 4500 kg = 8.33 m/s

Southward velocity component:

(50010 kg·m/s) / 4500 kg = 11.11 m/s

We combine these components to find the magnitude and direction of the final velocity:

Magnitude = √((8.33 m/s)² + (11.11 m/s)²)

or, Magnitude = √(69.39 + 123.4)

Magnitude ≈ 13.89 m/s

Direction: arctan(11.11 / 8.33)

Direction ≈ 53.12° south of east

So, the cars will move at a velocity of approximately 13.89 m/s in a direction that is 53.12 degrees south of east after the collision.

Final answer:

To determine the radius of the satellite's circular orbit, use Kepler's third law.

Explanation:

To determine the radius of the satellite's circular orbit, we can use Kepler's third law, which states that the period of an orbit is related to the radius of the orbit. The formula for Kepler's third law is:

T² = (4π²*r³) / (G*M)

Where T is the period, r is the radius, G is the gravitational constant, and M is the mass of the Earth. We are given the period of the satellite (6560 s) and the mass of the satellite (5420 kg), so we can solve for the radius using the formula.

T² = (4π²*r³) / (G*M)

6560² = (4π²*r³) / (6.67 x 10⁻¹¹ * 5.97 x 10²⁴)

Using this equation, we can solve for r, the radius of the satellite's circular orbit.

Explanation:

It is given that,

Mass of the car, m = 525 kg

Applied force, F = 375 N

The coefficient of friction felt by the car is 0.42, [tex]\mu=0.42[/tex]

(a) The weight of the car is given by :

[tex]W=mg[/tex]

[tex]W=525\times 9.8[/tex]

W = 5145 N

(b) The force of friction acts in the opposite direction of motion. It can be calculated as :

[tex]f=\mu mg[/tex]

[tex]f=0.42\times 5145[/tex]

f = 2160.9 N

(c) Here, the force of friction is greater than the applied force. As a result, the ball will not moves. So, the net force acting on this car is 0.

(d) As the net force acting on the car is 0. There will be no acceleration in the car.    

Final answer:

a. The force weight of the car is 5145 N. b. The force friction acting on the car is 216.09 N. c. The net force acting on the car is 158.91 N. d. The acceleration of the car is 0.714 m/s².

Explanation:

a. To calculate the force weight of the car, we can use the formula:

Force weight = mass * acceleration due to gravity

Given that the mass of the car (m) is 525 kg and the acceleration due to gravity (g) is 9.8 m/s², we can substitute these values into the formula:

Force weight = 525 kg * 9.8 m/s² = 5145 N

So, the force weight of the car is 5145 N.

b. To calculate the force friction acting on the car, we can use the formula:

Force friction = coefficient of friction * force weight

Given that the coefficient of friction (µ) is 0.0420 and the force weight is 5145 N, we can substitute these values intothe formula:

Force friction = 0.0420 * 5145 N = 216.09 N

So, the force friction acting on the car is 216.09 N.

c. The net force acting on the car can be calculated by subtracting the force friction from the force applied by the engine:

Net force = force applied - force friction

Given that the force applied by the engine is 375 N and the force friction is 216.09 N, we can substitute these values into the formula:

Net force = 375 N - 216.09 N = 158.91 N

So, the net force acting on the car is 158.91 N.

d. To calculate the acceleration of the car, we can use Newton's second law of motion:

Force = mass * acceleration

Given that the force applied by the engine is 375 N and the mass of the car is 525 kg, we can substitute these values into the formula:

375 N = 525 kg * acceleration

Solving for acceleration:

acceleration = 375 N / 525 kg = 0.714 m/s²

So, the acceleration of the car is 0.714 m/s².

The force experienced by a positively charged particle moving westward and just north of a wire with a current directed east will be downward, based on the right-hand rule of electromagnetism.

The scenario described involves a current-carrying wire and the motion of a charged particle, both of which invoke the concept of the magnetic force as per the right-hand rule in electromagnetism. According to this rule, if we point the thumb of our right hand in the direction of the current (which in this case is east), and our fingers in the direction of the velocity of the positive charge (which is west), then the palm faces toward the direction of the force on a positive charge. Since the charge is moving just north of the wire, the magnetic field will be directed towards the earth's surface (downwards if we consider the conventional 3D coordinate system). Therefore, the resulting force experienced by the positively charged particle will be downward, towards the ground.

The strength of an electric field (E) can be determined using the formula:

[tex]\[ E = \frac{F}{q} \][/tex]

where:

- [tex]\( E \)[/tex] is the electric field strength,

- [tex]\( F \)[/tex] is the force experienced by the charge,

- [tex]\( q \)[/tex] is the magnitude of the charge.

In this case, the given values are:

- [tex]\( F = 4.5 \times 10^{-4} \, \text{N} \) (force)[/tex],

- [tex]\( q = 6.0 \times 10^{-4} \, \text{C} \) (charge)[/tex].

Now, plug these values into the formula:

[tex]\[ E = \frac{4.5 \times 10^{-4} \, \text{N}}{6.0 \times 10^{-4} \, \text{C}} \][/tex]

[tex]\[ E = \frac{4.5}{6.0} \, \text{N/C} \][/tex]

[tex]\[ E = 0.75 \, \text{N/C} \][/tex]

Therefore, the strength of the electric field is [tex]\(0.75 \, \text{N/C}\)[/tex].

Given the force acting on the object, the change in its momentum is 4kg.m/s.

To determine the object's change in momentum, we use the Impulse Momentum Theorem:

The impulse applied to a body or matter is equal to the change in its momentum

Impulse = Change in Momentum

[tex]Impulse = F * dt[/tex]

Where F is the force applied and [tex]dt[/tex] is the elapsed time

Hence

[tex]Change \ in \ Momentum = F * dt[/tex]

We substitute our given values into the equation

[tex]Change \ in \ Momentum = 8 kg.m/s^2 * 0.50s\\\\Change \ in \ Momentum =4kg.m/s[/tex]

Therefore, given the force acting on the object, the change in its momentum is 4kg.m/s.

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Answer:

197.83 m^2

Explanation:

F = 6500 N, A = ?

f = 230 N, a = 7 m^2

Let the area of piston beneath the automobile is A.

By use of Pascal's law

F / A = f / a

6500 / A = 230 / 7 A = 197.83 m^2

The most accurate description of a risk with using radioisotopes in nuclear reactors is the potential for radiation to leak and cause significant harm to living organisms which is described in option D. This includes the possibility of serious malfunctions in cell processes and the challenge of managing high-level radioactive waste.

The statement that best describes a risk associated with using radioisotopes in nuclear reactors is D: If the radiation were to leak out of the reactors, it could cause significant damage to living organisms. Radioactive emissions from radioisotopes can fragment or ionize molecules, which leads to the production of highly reactive ions and molecular fragments. This damage to biomolecules can cause disruptions in cell processes, leading to illness or death. Accidents or leaks from nuclear reactors can also result in the exposure of these radioisotopes to the environment, affecting humans, animals, and the ecosystem.

Moreover, the disposal of high-level radioactive waste generated from spent nuclear fuel is a significant concern. It presents long-term risks due to the potential leakage of radiation into the environment and the complex and costly processes required for safe disposal. Hence, although nuclear energy is a potent source without greenhouse gas emissions, the risks involving radiation leaks and waste management are genuine concerns.

Answer:

2 km south

Explanation:

In order to calculate this you just have to have in mind that your starting point will be 0, and as south and north are contrary, one of the will benegative, in this case we will take south as negative, so lets begin:

-4 km south

+2 km north

-5 km south

+5 km north

This equals -2 km, since it is negative we know that it´s south, so the displacement after all will be 2 kilometers south from the starting point.

A horizontal line on a speed vs. time graph signifies that the object is maintaining a constant velocity because there is no change in speed over time.

A horizontal line above the time axis of a speed vs. time graph indicates that an object is travelling at a constant velocity. This is because the speed does not change over time, and thus the graph shows a straight line parallel to the time axis, with no slope. When examining an acceleration vs. time graph, a horizontal line at zero would mean the acceleration is zero, which aligns with the object maintaining a constant speed, as acceleration is the rate of change of velocity.

Final answer:

Thermal conduction in solids occurs as atoms and molecules rapidly move or vibrate, transferring kinetic energy to neighboring particles, and through movement of electrons, facilitating heat transfer without the mass flow characteristic of convection.

Explanation:

On a particle level, when thermal conduction occurs within a solid, rapidly moving or vibrating atoms and molecules transfer some of their kinetic energy to adjacent particles. This is the principal means for heat transfer within a solid, with the close fixed spatial relationships between atoms in a solid facilitating this transfer by vibration. Heat is also transferred by the movement of electrons from one atom to another. Unlike convection which occurs in fluids, heat transfer by conduction in solids does not involve large-scale flow of matter.

For example, the heat from an electric burner transfers to the bottom of a pan via conduction. The hot surface causes the atoms in the pan to vibrate more energetically, which then collide with neighboring atoms, spreading the heat throughout the pan. Conductive heat transfer efficiency is affected by the temperature difference, size and thickness of the material, as well as its thermal properties.

Answer : Electric potential is 600 V

Explanation :

It is given that,

Electric charge, [tex]q=4.5\times 10^{-5}\ C[/tex]

Electric potential energy, [tex]U=0.027\ J[/tex]

The relation between the electric potential and the electric potential energy is given by :

[tex]U=qV[/tex]

[tex]V=\dfrac{U}{q}[/tex]

[tex]V=\dfrac{0.027\ J}{4.5\times 10^{-5}\ C}[/tex]

[tex]V=600\ V[/tex]

Hence, the electric potential is 600 V.

The work done by tension is zero. The work done by friction is negative. The net work done is positive.

1) The work done by tension before the block gets to the incline is zero because the tension force is acting perpendicular to the displacement.

2) The work done by friction as the block slides on the flat horizontal surface is negative because the friction force is acting opposite to the displacement.

3) The speed of the block right before it begins to travel up the incline can be calculated using the work-energy theorem, which states that the work done on an object is equal to the change in its kinetic energy.

4) The distance up the incline that the block travels before coming to rest can be calculated using the work-energy theorem and the work done by friction.

5) The work done by gravity as the block comes to rest is zero since there is no displacement in the vertical direction.

6) The net work done on the block during the entire process is positive.

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Answer:

constructive + destructive.

Explanation:

edge 22.

This question is based on Boyle's law and Charles' law.

As per Boyle's law the volume of a given mass of a gas is inversely proportional to the applied pressure at constant temperature. Mathematically it can be written as

                               [tex]P\ \alpha \frac{1}{V}[/tex]     [at constant T and n]

Charles'law: It states that at constant pressure the volume of a given mass of a gas increases or decreases by 1/273 th of its volume at zero degree celsius for every 1 degree centigrade rise or fall of temperature.One may say that volume is directly proportional to temperature. Mathematically it can be written as

                                                    V∝T          [at constant P and n]

Here P,V,T and n stand for pressure,volume,temperature and number of moles respectively.

In the diagram given in the question the point X  is present in the region where Boyle's law is obeyed.Hence the correct option will be the third one which depicts the presence inverse relationship which is true for pressure and volume at constant temperature.

Answer:

T = 206 K

Explanation:

As we know by Wein's law of displacement that if we draw all radiations intensity with all possible wavelengths radiated from the object then the wavelength corresponding to maximum intensity of radiation is inversely dependent to the absolute temperature of the object.

So here we can say

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

here we know

b = Wein's constant

[tex]b = 2.89 \times 10^{-3}[/tex]

now we have

[tex]\lambda = 14000 nm[/tex]

from above equation

[tex]14000 \times 10^{-9} = \frac{2.89 \times 10^{-3}}{T}[/tex]

[tex]T = 206 K[/tex]

Transformers, specifically step-up transformers, are crucial for efficiently transmitting electrical energy from power plants to users by increasing the voltage, resulting in reduced current and minimization of Joule losses. High voltage transmission leads to greater efficiency and lower energy losses, making the process both economical and environmentally friendly.

The electrical device that makes it possible to transmit electrical energy efficiently from a power plant to users is the transformer. Transformers play a critical role in adjusting the voltage levels during the transmission of electric power over long distances. When power is generated, a step-up transformer increases the voltage from the power plant, which results in a proportional decrease in current and thus minimizes resistive power losses known as Joule losses. These minimized losses are crucial for maintaining efficiency since identical currents flow through both the load and transmission lines, where power is dissipated usefully in the load but wasted in the resistance of the transmission lines.

The solenoid must have about 2332 turns

[tex]\texttt{ }[/tex]

Let's recall magnetic field strength from current carrying wire and from center of the solenoid as follows:

[tex]\boxed {B = \mu_o \frac{I}{2 \pi d} } [/tex]

B = magnetic field strength from current carrying wire (T)

μo = permeability of free space = 4π × 10⁻⁷ (Tm/A)

I = current (A)

d = distance (m)

[tex]\texttt{ }[/tex]

[tex]\boxed {B = \mu_o \frac{I N}{L} } [/tex]

B = magnetic field strength at the center of the solenoid (T)

μo = permeability of free space = 4π × 10⁻⁷ (Tm/A)

I = current (A)

N = number of turns

L = length of solenoid (m)

Let's tackle the problem now !

[tex]\texttt{ }[/tex]

Given:

Current = I = 4.3 A

Length = L = 42 cm = 0.42 m

Magnetic field strength = B = 0.030 T

Permeability of free space = μo = 4π × 10⁻⁷ T.m/A

Asked:

Number of turns = N = ?

Solution:

[tex]B = \mu_o \frac{I N}{L}}[/tex]

[tex]\frac{I N}{L} = B \div \mu_o[/tex]

[tex]IN = BL \div \mu_o[/tex]

[tex]N = BL \div (\mu_o I)[/tex]

[tex]N = ( 0.030 \times 0.42 ) \div ( 4 \pi \times 10^{-7} \times 4.3 )[/tex]

[tex]\boxed {N \approx 2332}[/tex]

[tex]\texttt{ }[/tex]

[tex]\texttt{ }[/tex]

Grade: High School

Subject: Physics

Chapter: Magnetic Field