Practice 1.2C Solutions
Motion Graph 1
Multiple Choice
1.
Which of the following graphs could correctly represent the motion of an object moving with a constant
speed in a straight line?
Answer: C
Constant speed is a constant slope on a position-time graph, a horizontal line on a velocity time
graph or a zero value on an acceleration-time graph
(A) Graph I only (B) Graphs II and V only (C) Graph II only (D) Graphs I and IV only (E) All of the above graphs
represent constant velocity
2.
The graph above shows velocity v versus time t for an object in linear motion. Which of the following is a
possible graph of position x versus time t for this object?
Answer: A
A velocity-time graph represents the slope of the displacement-time graph. Analyzing the v-t
graph shows a constant slope, then a decreasing slope to zero, becoming negative and increasing,
then a constant slope. Note this is an analysis of the values of v, not the slope of the graph itself
Use the graph below to answer the following questions. The velocity vs. time graph for the motion of a car on a
straight track is shown in the diagram. The thick line
represents the velocity. Assume that the car starts at the origin x = 0.
3.
4.
At which time is the car the greatest distance from the origin?
(A) t = 10 s (B) t = 6 s (C) t = 5s (D) t = 3s (E) t = 0 s
The car is the greatest distance just before it reverses direction at 5 seconds.
What is the average speed of the car for the 10 second interval?
(A) 1.20 m/s (B) 1.40 m/s (C) 3.30 m/s (D) 5.00 m/s (E) 5.40 m/s
Average speed = (total distance)/(total time), the total distance is the magnitude of the area under
the line (the area below the t-axis is considered positive)
Free Response
Problem 1
A position vs time graph is shown to the right. Please
analyze the graph and determine the following. (a)
The speed of the object from b  c, (b) the speed
from c  d, (c) the speed from d  e, (d) the times t
when the speed of the object is zero, and (e) the points
where the direction of the object had to change (if
any).
x
5
b
c
e
a
10
5
5
15
d
Position Time Graph
t
Problem 2
Use the graph below to answer the following questions.
a) What was the cart's instantaneous speed at 11 seconds? (3m/s)
b) List two time intervals where the object has the same speed but different velocities. (2 m/sec: 4-10
seconds and 34-42 seconds)
c) For each interval, find the object’s displacement.
Time Interval
Displacement
0-4 s
4-10 s
d)
e)
f)
g)
What was the cart’s total displacement? (-4 m)
What was the cart's average velocity during these 46 seconds? (0.087 m/s)
What was the total distance the cart traveled for the entire 46 seconds? (64 m)
What was the cart's average speed during these 46 seconds? (1.39 m/s)
Problem 3
Above is a velocity v. time graph. Sketch the position time graph below. Assume the object’s initial position
is 0 m. Be sure to label the axes.