Chapter 2 - Describing Motion: Kinematics in One Dimension

Question 1

Consider a deer that runs from point A to point B. The distance the deer runs can be greater than the magnitude of its displacement, but the magnitude of the displacement can never be greater than the distance it runs.
A) True
B) False

Answer 1

A) True

Question 2

Which of the following quantities has units of a displacement? (There could be more than one correct choice.)
A) 32 ft/s2 vertically downward
B) 40 km southwest
C) 9.8 m/s2
D) -120 m/s
E) 186,000 mi

Answer 2

B) 40 km southwest
E) 186,000 mi

Question 3

3) When is the average velocity of an object equal to the instantaneous velocity?
A) only when the velocity is increasing at a constant rate
B) only when the velocity is decreasing at a constant rate
C) when the velocity is constant
D) always
E) never

Answer 3

C) when the velocity is constant

Question 4

You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h. Your average speed over the 12 km drive will be
A) greater than 70 km/h.
B) equal to 70 km/h.
C) less than 70 km/h.
D) exactly 38 km/h.
E) It cannot be determined from the information given because we must also know directions
traveled.

Answer 4

C) less than 70 km/h.

Question 5

If the velocity of an object is zero at some point, then its acceleration must also be zero at that point.
A) True
B) False

Answer 5

B) False

Question 6

An auto manufacturer advertises that their car can go “from zero to sixty in eight seconds.” This is a description of what characteristic of the car’s motion?
A) average speed
B) instantaneous speed
C) average acceleration
D) instantaneous acceleration
E) displacement

Answer 6

C) average acceleration

Question 7

Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point?
A) zero
B) slightly less than g
C) exactly g
D) slightly greater than g

Answer 7

C) exactly g

Question 8

A 10-kg rock and a 20-kg rock are dropped at the same time and experience no significant air resistance. If the 10-kg rock falls with acceleration a, what is the acceleration of the 20-kg rock?
A) 4a
B) 2a
C) a
D) a/2
E) a/4

Answer 8

C) a

Question 9

From the edge of a roof top you toss a green ball upwards with initial speed v0 and a blue ball downwards with the same initial speed. Air resistance is negligible. When they reach the ground
below
A) the green ball will be moving faster than the blue ball.
B) the blue ball will be moving faster than the green ball.
C) the two balls will have the same speed.

Answer 9

C) the two balls will have the same speed.