Question 1

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios.
-The elevator cable breaks.
A)150 lb
B)160 lb
C)170 lb
D)none of the above

Accepted Answer

The person in the elevator is in free fall when the cable breaks, so their apparent weight is equal to zero. The bathroom scale would not produce any reading, so the answer is none of the above.

Question 2

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -After moving downwards at constant speed,the elevator is slowing down at 2 m/s² as it is coming to rest. A)150 lb B)160 lb C)170 lb D)none of the above

Accepted Answer

When the elevator is slowing down while moving downwards, it is accelerating upwards. The apparent weight increases, so the scale reads more than the actual weight. The increase is due to the upward acceleration of 2 m/s², leading to a reading of 170 lb.

Question 3

At the highest point on the path of a projectile,its vertical acceleration
A)equals g pointing downwards.
B)equals g pointing upwards.
C)is zero.
D)is undetermined.
E)does not exist.

Accepted Answer

The answer of At the highest point on the path...

Question 4

Where is the Sun located relative to a planet's orbit about it?
A)at the center of the orbit,which is a circle
B)at the center of the orbit,which is an ellipse
C)at one focus of the ellipse which forms the orbit
D)none of the above

Accepted Answer

The Sun is located at one focus of the elliptical orbit which forms the orbit of each planet. This is one of Kepler's laws of planetary motion.

Question 5

You throw a ball straight up,it peaks out,and then comes back down to you.During this motion,the velocity and acceleration
A)always point in the same direction.
B)always point opposite to each other.
C)sometimes point in the same direction,and other times point opposite to each other.
D)depend on the way the ball is thrown.
E)depend on the mass of the ball.

Accepted Answer

When the ball is thrown upwards, its velocity is in the upward direction and acceleration is downward (due to gravity). At the highest point or peak, the velocity is momentarily zero (changing its direction from upward to downward) while the acceleration is still acting downwards. As the ball falls back down, its velocity is in the downward direction while the acceleration remains in the same direction as before. So the velocity and acceleration have different directions during different parts of the motion, i.e. at the peak they are opposite to each other, while during the ascent and descent they are in the same direction.

Question 6

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -The elevator is accelerating downwards at 2 ft/s². A)150 lb B)160 lb C)170 lb D)none of the above

Accepted Answer

When the elevator accelerates downwards, the apparent weight decreases. The apparent weight is calculated as: apparent weight = true weight - mass * acceleration. Here, true weight = 160 lb, mass = 5 slugs, and acceleration = 2 ft/s². Apparent weight = 160 lb - (5 slugs * 2 ft/s² * 32 lb/slug) = 160 lb - 10 lb = 150 lb.

Question 7

The horizontal speed of a projectile
A)is zero.
B)stays constant.
C)continuously increases.
D)continuously decreases.
E)sometimes decreases and sometimes increases.

Accepted Answer

The horizontal speed of a projectile stays constant because there's no force acting on it horizontally. Horizontal motion is not affected by gravity, and so the projectile continues moving at a constant speed unless acted upon by an external force.

Question 8

As a body falls through air starting from rest,its velocity
A)stays constant.
B)continuously decreases.
C)continuously increases.
D)gets larger and larger,eventually reaching a constant value.
E)gets smaller and smaller,eventually approaching zero.

Accepted Answer

As a body falls through air, its velocity increases due to gravity until it reaches terminal velocity, where the force of air resistance equals the gravitational force, causing the velocity to become constant.

Question 9

For this situation, I push on a heavy chair.
-Suppose I push very hard on the chair,and this time the chair moves and I slip backward as well.Then the strength of the force the chair exerts on me is
A)less than the force I exert on the chair.
B)equal to the force I exert on the chair.
C)greater than the force I exert on the chair.
D)zero.

Accepted Answer

According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In this situation, I am exerting a force on the chair, and the chair is exerting an equal force back on me, causing me to slip backward. Therefore, the strength of the force the chair exerts on me is equal to the force I exert on the chair.

Question 10

A body is oscillating up and down at the end of a spring. Let’s consider when the body is at the top of its up-and-down motion.
-The velocity
A)is zero.
B)has its largest magnitude.
C)points up.
D)points down.

Accepted Answer

At the top of its up-and-down motion, the body comes momentarily to rest before reversing its direction. Therefore, its velocity is zero at that point.

Question 11

For this situation, I push on a heavy chair.
-Suppose I push moderately on the chair,and this time the chair does move.Then the strength of the force the chair exerts on me is
A)less than the force I exert on the chair.
B)equal to the force I exert on the chair.
C)greater than the force I exert on the chair.
D)zero.

Accepted Answer

According to Newton's third law of motion, for every action, there is an equal and opposite reaction. When I push on the chair with a moderate force, the chair moves because there is a force of the same magnitude and direction acting back on me, which is provided by the chair. Therefore, the strength of the force the chair exerts on me is equal to the force I exert on the chair.

Question 12

The vertical acceleration of a projectile
A)equals g pointing downwards.
B)equals g pointing upwards.
C)equals g pointing sometimes upwards and other times downwards.
D)is zero.
E)continuously increases.

Accepted Answer

The vertical acceleration of a projectile is equal to the acceleration due to gravity, which always acts in the downward direction. Therefore, the correct answer is A, which states that the vertical acceleration equals g pointing downwards.

Question 13

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios.
-The elevator accelerates downwards and is now moving at a constant speed.
A)150 lb
B)160 lb
C)170 lb
D)none of the above

Accepted Answer

When the elevator moves at a constant speed, the scale reads the actual weight of the person, which is 160 lb.

Question 14

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -After moving upwards at constant speed,the elevator is slowing down at 2 m/s² as it is coming to rest. A)150 lb B)160 lb C)170 lb D)none of the above

Accepted Answer

When the elevator is slowing down while moving upwards, the net force is downward, reducing the normal force. The scale reads less than the actual weight, hence 150 lb.

Question 15

The horizontal acceleration of a projectile
A)is zero.
B)stays constant.
C)continuously increases.
D)continuously decreases.
E)sometimes decreases and sometimes increases.

Accepted Answer

The horizontal acceleration of a projectile is always zero due to the absence of external forces acting on the projectile in the horizontal direction. Once the projectile is launched, the only force acting on it is gravity which only affects its vertical motion. Therefore, the horizontal velocity of the projectile remains constant unless affected by external forces such as air resistance or wind.

Question 16

The vertical speed of a projectile
A)is zero.
B)stays constant.
C)continuously increases.
D)continuously decreases.
E)sometimes decreases and sometimes increases.

Accepted Answer

The vertical speed of a projectile is affected by gravity, causing it to decrease as it moves upwards and increase as it moves downwards.

Question 17

Planetary orbits are
A)parabolas.
B)ellipses.
C)circles.
D)none of the above.

Accepted Answer

Planetary orbits are ellipses, specifically Keplerian ellipses. This was discovered by Johannes Kepler in the early 17th century and is now a fundamental principle of modern astronomy.

Question 18

As a body falls through air starting from rest,its acceleration
A)is zero.
B)stays constant.
C)continuously decreases.
D)continuously increases.
E)gets smaller and smaller,eventually approaching zero.

Accepted Answer

As the body falls through the air, the air resistance increases, causing the acceleration to decrease until it eventually approaches zero.

Question 19

Two cars crash head on.At any given time during the crash,the magnitudes of the collision forces exerted on each car are exactly equal.This is an example of Newton's
A)first law.
B)second law.
C)third law.
D)no law.

Accepted Answer

This scenario is an example of Newton's third law, which states that for every action, there is an equal and opposite reaction. In this case, as the two cars collide, each car exerts a force on the other that is equal in magnitude but opposite in direction. This is why the collision forces are exactly equal.

Question 20

For this situation, I push on a heavy chair.
-Suppose I push lightly on the chair,and the chair doesn't move at all.Then the strength of the force the chair exerts on me is
A)less than the force I exert on the chair.
B)equal to the force I exert on the chair.
C)greater than the force I exert on the chair.
D)zero.

Accepted Answer

According to Newton's third law of motion, every action has an equal and opposite reaction. Therefore, the force exerted by the chair on me will be equal and opposite to the force I exert on the chair. In this case, since the chair doesn't move and I push lightly, it means that the force I exert on the chair is equal to the force the chair exerts on me.

Quiz 2: Newtons Laws

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -The elevator cable breaks.

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -After moving downwards at constant speed,the elevator is slowing down at 2 m/s2 as it is coming to rest.

At the highest point on the path of a projectile,its vertical acceleration

Where is the Sun located relative to a planet's orbit about it?

You throw a ball straight up,it peaks out,and then comes back down to you.During this motion,the velocity and acceleration

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -The elevator is accelerating downwards at 2 ft/s2.

The horizontal speed of a projectile

As a body falls through air starting from rest,its velocity

For this situation, I push on a heavy chair. -Suppose I push very hard on the chair,and this time the chair moves and I slip backward as well.Then the strength of the force the chair exerts on me is

A body is oscillating up and down at the end of a spring. Let’s consider when the body is at the top of its up-and-down motion. -The velocity

For this situation, I push on a heavy chair. -Suppose I push moderately on the chair,and this time the chair does move.Then the strength of the force the chair exerts on me is

The vertical acceleration of a projectile

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -The elevator accelerates downwards and is now moving at a constant speed.

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -After moving upwards at constant speed,the elevator is slowing down at 2 m/s2 as it is coming to rest.

The horizontal acceleration of a projectile

The vertical speed of a projectile

Planetary orbits are

As a body falls through air starting from rest,its acceleration

Two cars crash head on.At any given time during the crash,the magnitudes of the collision forces exerted on each car are exactly equal.This is an example of Newton's

For this situation, I push on a heavy chair. -Suppose I push lightly on the chair,and the chair doesn't move at all.Then the strength of the force the chair exerts on me is

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -After moving downwards at constant speed,the elevator is slowing down at 2 m/s² as it is coming to rest.

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -The elevator is accelerating downwards at 2 ft/s².

A 160 lb person has a mass of 160/32 = 5 slugs.A 160-lb person steps into an elevator and stands on a bathroom scale.Determine the scale reading for the given scenarios. -After moving upwards at constant speed,the elevator is slowing down at 2 m/s² as it is coming to rest.