Semester Exam Concept Questions

Question 1

An object with a positive velocity and a negative acceleration must be __________.

Answer 1

slowing down, moving in the positive direction, acted on by a negative net force

Question 2

Consider a ball thrown straight up. At the apex, its acceleration is _________.

Answer 2

g, negative, -9.8 m/s^2

Question 3

A ball is thrown forward at 10 m/s from the top of a building 90m tall. The initial vertical velocity of the ball is _____.

Answer 3

zero

Question 4

A ball is thrown forward at 10 m/s from the top of a building 90m tall. During its flight, the horizontal acceleration of the ball is _____.

Answer 4

zero

Question 5

The slope of a velocity vs. time graph equals _________.

Answer 5

acceleration

Question 6

If an object is at rest and staying at rest, then ______________.

Answer 6

the net force on it is zero, acceleration is zero

Question 7

If an object is accelerating while only 2 forces act on it, __________________.

Answer 7

the forces do not balance, the net force is not zero

Question 8

An object has only 2 forces acting on it which are equal in magnitude. If the object is accelerating, _____________.

Answer 8

the forces are not acting in opposite directions, the net force does not equal zero

Question 9

Consider these two masses released on an atwood machine: 3m and m. What is the same for both masses as they move?

Answer 9

speed, magnitude of acceleration, tension force, distance, two forces acting

Question 10

Consider these two masses released on an atwood machine: 3m and m. What is different for both masses as they move?

Answer 10

net force, mass, weight, kinetic energies, gravitational potential energy, acceleration, displacement, momentum, work done on them, power

Question 11

Consider these two masses released from rest in deep space when their centers are a distance d apart: 4m and m. What is the same for both as they move?

Answer 11

magnitude of gravitational force of attraction, magnitude of momentum, magnitude of net force

Question 12

Consider these two masses released from rest in deep space when their centers are a distance d apart: 4m and m. What is different for both as they move?

Answer 12

force, acceleration, speed, momentum, distance traveled, displacement

Question 13

As a car rounds a turn in uniform circular motion, what is changing?

Answer 13

velocity, centripetal acceleration, centripetal force

Question 14

As a car rounds a turn in uniform circular motion, what is constant?

Answer 14

speed, magnitude of centripetal acceleration, magnitude of centripetal force, radius, period, frequency, magnitude of normal force

Question 15

What happens to the centripetal force required to keep an object in uniform circular motion if its mass, velocity, and radius of motion are all doubled?

Answer 15

centripetal force is quadrupled

Question 16

These 2 railroad cars will lock together upon collision: 4m (3v) –> m (v) Ignore friction with the track. What will be different for both during the collision?

Answer 16

force, impulse, change in velocity

Question 17

These 2 railroad cars will lock together upon collision: 4m (3v) –> m (v) Ignore friction with the track. What will be the same for both during the collision?

Answer 17

time, magnitude of force, magnitude of impulse, final velocity

Question 18

These 2 railroad cars will lock together upon collision: 4m (3v) –> m (v) Ignore friction with the track. What will the velocity of the joined cars be right after the collision?

Answer 18

(13/5)v

Question 19

4m (3v) –> m (v)
If these cars do not stick together, the impulse of the car with mass m will be

A. more than if they stuck together
B. less than if they stuck together
C. the same as if they stuck together

Answer 19

A. more than if they stuck together