The graph in the figure shows the position of a particle as it travels along the x-axis.What is the magnitude of the average velocity of the particle between t = 1.0 s and t = 4.0 s?
A)0.25 m/s
B)0.50 m/s
C)0.67 m/s
D)1.0 m/s
E)1.3 m/s

Question

The graph in the figure shows the position of a particle as it travels along the x-axis.What is the magnitude of the average velocity of the particle between t = 1.0 s and t = 4.0 s? 
A)0.25 m/s 
B)0.50 m/s 
C)0.67 m/s 
D)1.0 m/s 
E)1.3 m/s

Quizplus · Accepted Answer

The magnitude of the average velocity between two points on a position vs time graph is equal to the slope of the straight line connecting those two points.

Taking the points at t=1s and t=4s, we can draw a straight line connecting them, and find its slope. The slope of the line is the change in position divided by the change in time, i.e.,

slope = (2 m - 3 m) / (4 s - 1 s) = (-1 m) / (3 s)

Note that the velocity is negative because the particle is moving in the negative direction (i.e., towards the left on the x-axis).

The magnitude of the average velocity is the absolute value of the slope, so

magnitude of velocity = | slope | = |-1/3| = 1/3 m/s

Therefore, the best choice is C, 0.67 m/s.

The Graph in the Figure Shows the Position of a Particle