Quiz 1

Question 1

You toss a ball straight upward, in the positive direction. The ball falls freely under the influence of gravity.

At the highest point in the ball’s motion,

A. its velocity is zero and its acceleration is zero.
B. its velocity is zero and its acceleration is positive (upward).
C. its velocity is zero and its acceleration is negative (downward).
D. its velocity is positive (upward) and its acceleration is zero.
E. its velocity is positive (upward) and its acceleration is zero

Answer 1

C. its velocity is zero and its acceleration is negative (downward).

Question 2

The position of an moving along the x-axis is given by
x = (5.0m/s)t - (10.0 m/s^2) t^2 + (4.0 m/s^3)t ^3
What is the object doing at t = 1.0 s?

A. It is moving and speeding up
B. It is moving and slowing down
C. It is moving, but its velocity is not changing at this instant
D It is momentarily at rest D. It is momentarily at rest
E. Not enough information given to decide

Answer 2

B. It is moving g and slowing down

Question 3

You are given the vx-t graph for an object moving along the x-axis with constant acceleration. Which of the
following could you not determine from the information given in this graph alone?

A. the object’s x-acceleration at any time t
B. the object’s x-velocity at any time t
C. the object’s position at any time t
D. more than one of the above
E. misleading question—you could determine
all of these from the vx-t graph alone

Answer 3

C. the object’s position at any time t

Question 4

The position of an object moving along the x-axis is given by
x = 5.0 m – (4.0 m/s)t + (2.0 m/s2)t2
Which statement about this object is correct?

A. For t > 0, the object is never at rest.
B. The object is at rest at t = 0.5 s.
C The object is at rest at t = 1.0s
D. The object is at rest at t = 2.0 s.
E. More than one of B, C, and D is correct.

Answer 4

C The object is at rest at t = 1.0s

Question 5

The position of an object moving along the x-axis is given by axis is given by
x = 5.0 m – (4.0 m/s)t + (2.0 m/s2)t2
How many times does this object pass through the point x = 0?

A. twice, first moving in the positive x-direction,
then moving in the negative x-direction
B. twice, first moving in the negative x-direction,
then moving in the positive x-direction
C. only once, moving in the positive x-direction
D. only once, moving in the negative x-direction
E. never

Answer 5

E. never

Question 6

If you toss a ball upward with a certain initial speed, it falls freely and reaches a maximum height h.
By what factor must you increase the initial speed of the ball for
it to reach a maximum height 3h?

A. sqrt. 3
B. 3
C. 3sqrt. 3
D. 9
E. 27

Answer 6

A. sqrt. 3

Question 7

You are given the vx-t graph for an object moving along
h i i h l i Whi h f h
Q2.13
t e x-axis with constant acceleration. Which of the
following could you not determine from the information
g gp iven in this graph alone?
A. the object’s x-acceleration at any time t
B. the object’s x-velocity at any time t
C. the object’s position at any time t
D. more than one of the above
E. misleading question—you could determine
all of these from the vx-t graph alone