Exam 2: Quiz Questions

Question 1

When using the term “uniform circular motion,” what do we mean by the term “uniform?”

a) The direction of the object’s velocity is constant.
b) The net force on the moving object is zero newtons.
c) The forces acting on the object are uniformly applied from all directions.
d) The motion occurs without the influence of the gravitational force.
e) The motion of the object is at a constant speed.

Answer 1

E) the motion of the object @ a constant speed

Question 2

For an object in uniform circular motion, which one of the following statements is false ?

a) The velocity of the object is constant.
b) The magnitude of the acceleration of the object is constant.
c) The acceleration is directed radially inward.
d) The magnitude of the velocity is constant.
e) The velocity is directed in a direction that is tangent to the circular path.

Answer 2

a) the velocity of the object is constant

Question 3

A satellite orbits the Earth in uniform circular motion. What is the direction of centripetal acceleration of the satellite?

a) Because the centripetal acceleration is a scalar quantity, it doesn’t have a direction.
b) The centripetal acceleration vector points radially outward from the Earth.
c) The centripetal acceleration vector points radially inward toward the Earth.
d) The centripetal acceleration vector points in the direction of the satellite’s velocity.
e) The centripetal acceleration vector points in the direction opposite that of the satellite’s velocity.

Answer 3

c) the a (centripetal) vector points radially inward toward the Earth

Question 4

The centripetal force is best explained by which of the following statements?

a) The centripetal force is the force on an object that is directed radially outward from the center of its orbit.
b) The centripetal force is the force on an orbiting object that is directed along a line that is tangent to the circle.
c) The centripetal force is the net force acting on an orbiting object that maintains it in uniform circular motion.
d) The centripetal force is a fundamental force of nature.

Answer 4

c) The centripetal force is the net force acting on an orbiting object that maintains it in uniform circular motion.

Question 5

The maximum speed at which a car can safely negotiate a frictionless banked curve depends on all of the following except

a) the acceleration due to gravity.
b) the radius of the curve.
c) the angle of banking.
d) the diameter of the curve.
e) the mass of the car.

Answer 5

e) the mass of the car

Question 6

The period of a satellite orbiting Earth does NOT depend on which one of the following quantities?

a) the mass of the satellite
b) the mass of the Earth
c) the distance from the center of the Earth to the satellite
d) G, the universal gravitational constant

Answer 6

a) the mass of the satellite

Question 7

At a circus, a clown on a motorcycle travels along a horizontal track and enters a vertical circle. What minimum acceleration must the motorcycle have at the top of the track to remain in contact with the track?

a) 19.6 m/s^2, upward
b) 4.9 m/s^2, upward
c) 9.8 m/s^2, upward
d) 4.9 m/s^2, downward
e) 9.8 m/s^2, downward

Answer 7

9.8 m/s^2 downward

Question 8

A steel ball is tied to the end 
of a string and swung in a vertical 
circle at constant speed.  Complete the following statement: The direction of the instantaneous velocity of the ball is always
a)  perpendicular to the circle.
b)  toward the center of the circle.
c)  tangent to the circle.
d)  radially outward from the circle.
e)  vertically downward.

Answer 8

c) tangent to the circle

Question 9

Work may be expressed using all of the following units except:

a) watt
b) joule
c) Nm
d) erg
e) ftlb

Answer 9

a) Watt

Question 10

Which one of the following is not a unit of energy?

a) joule
b) watt
c) newtonmeter
d) kilowatthour
e) foot*pound

Answer 10

b) Watt

Question 11

In which one of the following circumstances does the force do positive work on the object?

a) The direction of the force is perpendicular to the object’s displacement.
b) The direction of the force is in the opposite direction to the object’s displacement.
c) No matter the direction of the force, positive work will be done if there is a displacement of the object.
d) The direction of the force is in the same direction as the object’s displacement.
e) The object’s displacement is zero meters as the force is applied.

Answer 11

d) the direction of the force is in the same direction as the object’s displacement

Question 12

Which one of the following is an example of an object with a non-zero kinetic energy?

a) A train is parked in a train station.
b) A car rests at the top of a hill.
c) The pendulum of a grandfather clock is still.
d) A boulder rests at the bottom of a cliff.
e) The International Space Station orbits the Earth.

Answer 12

e) The international space station orbits the Earth

Question 13

Which one of the following expressions is equal to the kinetic energy of an object?

a) mvt2
b) (1/2)mv^2
c) Fd cos (angle)
d) ma
e) mgh

Answer 13

b) (1/2)mv^2

Question 14

In which one of the following systems is there a decrease in gravitational potential energy?

a) A large boulder rests at the bottom of a steep hill.
b) A helicopter takes off from the roof of a hospital and flies due west.
c) A child accidentally releases a helium-filled balloon and it flies upward into the clouds.
d) A girl jumps down from a bed and lands on her feet.
e) A truck drives at an average velocity of 25 m/s, due north along a level, country road.

Answer 14

d) A girl jumps down from a bed and lands on her feet

Question 15

An arrow is launched straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the arrow as it rises? Neglect air resistance.

a) The kinetic energy of the arrow increases and its potential energy decreases.
b) Both the potential energy of the arrow and its total energy increase.
c) The kinetic energy of the arrow decreases as the potential energy increases.
d) Both the kinetic energy of the arrow and its potential energy remain constant.
e) The total energy of the arrow increases.

Answer 15

c) the kinetic energy of the arrow decreases as the PE increases

Question 16

Alice and Bill, who happen to have the same mass, both want to climb to the top of a mountain. Bill wants to take the steep path straight up, but Alice wants to take the path that gently winds around the mountain, even though it is 8 times longer than the steep path. They both eventually reach the top of the mountain,
but Alice reaches the top in 1/3 the time that Bill takes using the steep route. How does the work that Alice did in climbing the mountain compare with the amount that Bill did?
a) Alice did 1/8 the amount of work that Bill did.
b) Alice did 1/3 the amount of work that Bill did.
c) Alice and Bill did the same amount of work.
d) Alice did twice the amount of work that Bill did.
e) Alice did three times the amount of work that Bill did.

Answer 16

c) Alice & Bill did the same amount of work

Question 17

What is the relationship between the gravitational potential energy of an object and the work done on the object by the gravitational force?

a) The work is equal to the gravitational potential energy.
b) The negative of the work is equal to the change in the gravitational potential energy.
c) The negative of the work is equal to the square of the gravitational potential energy.
d) The work is equal to the square of the gravitational potential energy.
e) The work is equal to one-half of the gravitational potential energy.

Answer 17

b) the negative of the work is equal to the square of the gravitational PE

Question 18

Which one of the following situations is an example of a conservative force acting?

a) A boat motor produces a propulsion force that moves the boat across a lake.
b) The tension force in the rope increased as the piano was lifted off the ground.
c) A child jumping on a trampoline is pushed upward by an elastic spring force.
d) A normal force pushes upward on a book as it sits on a table.
e) The static frictional force between the tires of a car and the road.

Answer 18

c) the child jumping on a trampoline is pushed upward by an elastic spring force

Question 19

Complete the following statement: The net work done by a conservative force acting on an object

a) depends only on the time that the force is exerted.
b) depends only on the velocity of the object.
c) depends only on the starting and ending points.
d) is always equal to zero joules.
e) is always greater than zero joules.

Answer 19

c) depends only on the starting and ending points

Question 20

Which one of the following statements concerning the principle of the conservation of mechanical energy is true?

a) Mechanical energy is always conserved in situations where the kinetic energy is constant.
b) Mechanical energy is always conserved in situations where the gravitational potential energy is constant.
c) Mechanical energy is always conserved in situations where external non-conservative forces do no work.
d) Mechanical energy is always conserved in situations where external conservative forces do no work.
e) Mechanical energy is always conserved in situations where the gravitational potential energy is zero joules.

Answer 20

c) mechanical energy is always conserved in situations where external non-conservative forces do no work

Question 21

Complete the following statement: The total mechanical energy of a system remains unchanged if

a) the external forces acting on the system are nonconservative.
b) the external forces acting on the system are conservative.
c) the kinetic energy is constant.
d) the potential energy is constant.
e) there are no external forces acting on the system.

Answer 21

e) there are no external forces acting on the system

Question 22

Complete the following statement: In situations involving non-conservative external forces, the work done by these forces

a) is always negative.
b) is always equal to zero.
c) is always positive.
d) can be either positive or negative.
e) usually cannot be determined.

Answer 22

a) is always negative

Question 23

The power due to a force depends on which of the following parameters?

a) the magnitude of the force and the displacement of the object
b) the magnitude of the force and the velocity of the object
c) the mass of the object and the velocity of the object
d) the work done on the object and its displacement
e) the mass of the object and the displacement of the object

Answer 23

b) the magnitude of the force and the velocity of the object

Question 24

Which one of the following statements is true concerning momentum?

a) Momentum is a force.
b) Momentum is a velocity.
c) Momentum is a scalar quantity.
d) The momentum of an object is always positive.
e) Momentum and impulse are measured in the same units.

Answer 24

e) Momentum and impulse are measured in the same units

Question 25

Momentum may be expressed using which of the following units? a) N/s b) kg/m c) kg*m/s d) kg/(m*s) e) N*kg/s

Answer 25

C) kg*m/s

Question 26

Complete the following statement: The change in momentum with respect to time for an object a) is always positive. b) is always equal to zero. c) has a constant value if the force acting on the object is conservative. d) is equal in magnitude to the net force acting on the object, but opposite in direction. e) is a scalar quantity that may be negative, zero, or positive.

Answer 26

c) has a constant value if the force acting on the object is conservative

Question 27

Which one of the following statements is true concerning momentum? a) Momentum is a force. b) Momentum is a velocity. c) Momentum is a scalar quantity. d) The momentum of an object is always positive. e) Momentum is measured in kg*m/s

Answer 27

e) momentum is measured in kg*m/s

Question 28

Which one of the following quantities is equal to the change in momentum of an object during a collision? a) impulse b) net force c) work d) change in kinetic energy e) maximum force

Answer 28

a) impulse

Question 29

A rocket is propelled forward as very high speed gases are ejected out of its back. Which one of the following is the best explanation as to why the rocket is propelled forward? a) The rocket is propelled forward due to the conservation of energy. b) The rocket is propelled forward due to the conservation of momentum. c) Because the gases are pushing against the air, the air propels the rocket forward. d) The rocket is propelled forward because both energy and momentum must be conserved. e) The high speed gases push on the rocket as they are ejected and propel it forward.

Answer 29

b) the rocket is propelled forward because both energy and momentum must be conserved

Question 30

A rifle of mass M is initially at rest. A bullet of mass m is fired from the rifle with a velocity v relative to the ground. Which one of the following expressions gives the velocity of the rifle relative to the ground after the bullet is fired. a) -mv b) mv c) Mv/m d) mv/M e) mv/M

Answer 30

d) mv/M

Question 31

A collision between two objects is elastic. Which one of the following statements concerning this situation is true? a) The total kinetic energy of the objects is the same before and after the collision. b) The total momentum of the objects is zero kg*m/s after the collision. c) The objects stick together and move as one object after the collision. d) The kinetic energy of the objects is zero joules after the collision. e) The vector sum of the velocities of the two objects is equal to zero m/s after the collision.

Answer 31

a) the TOTAL kinetic energy of the objects (both of them) is the same as before and after the collision

Question 32

A collision between two objects is inelastic. Which one of the following statements concerning this situation is true? a) The vector sum of the velocities of the two objects is equal to zero m/s after the collision. b) The total momentum of the objects after the collision is less than it was before the collision. c) The objects bounce away from each other after the collision. d) The kinetic energy of the objects is zero joules after the collision. e) The total kinetic energy of the objects after the collision is less than it was before the collision.

Answer 32

e) the total KE of the objects after the collision is less than it was before the collision

Question 33

Two objects are involved in an elastic collision. Which one of the following statements concerning this situation is false? a) The total momentum is conserved. b) The magnitude of the force exerted by each object on the other object is equal. c) The kinetic energy of each object is the same before and after the collision. d) The total kinetic energy before the collision is equal to the total kinetic energy after the collision. e) The total kinetic energy is conserved.

Answer 33

c) the KE of EACH object is the same as before/after the equation (FALSE)

Question 34

Which one of the following quantities is conserved during an elastic collision, but not conserved during an inelastic collision? a) momentum b) kinetic energy c) total energy d) impulse e) net force

Answer 34

b) KE

Question 35

Which one of the following statements concerning the center of mass of an object is true? a) The velocity of the center of mass of a system of objects is constant when the sum of the external forces acting on the system is zero. b) The center of mass of a system of objects cannot change even if there are forces acting on the objects. c) All of an object’s mass is located at its center of mass. d) The velocity of the center of mass of a system of objects is greatly affected by a collision of objects within the system. e) The center of mass of an object must be located within the object.

Answer 35

a) the velocity of the center of mass of a system of objects is constant when the sum of the external forces acting on the system is zero

Question 36

``` Three objects are located in the x-y plane as shown in the figure. Determine the x coordinate of the center of mass for this system of three objects. Note the masses of the objects: mA= 6.0 kg, mB= 2.0 kg, and mC= 4.0 kg. A is (2,12), B is (12,10), and C is (10, 2) a) 5.6 b) 6.3 c) 7.6 d) 8.3 e) 8.9 ```

Answer 36

b) 6.3

Question 37

Bird A, with a mass of 2.2 kg, is stationary while Bird B, with a mass of 1.7 kg, is moving due north from Bird A at 3 m/s. What is the velocity of the center of mass for this system of two birds? a) 1.4 m/s, due north b) 0.77 m/s, due north c) 1.7 m/s, due north d) 0.77 m/s, due south e) 1.4 m/s, due south

Answer 37

a) 1.4 m/s, due North