Solution Found!
Answer: A ball moves in a straight line (the x-axis). The
Chapter 2, Problem 9E(choose chapter or problem)
A ball moves in a straight line (the 𝑥-axis). The graph in Fig. E2.9 shows this ball’s velocity as a function of time. (a) What are the ball’s average speed and average velocity during the first 3.0 s? (b) Suppose that the ball moved in such a way that the graph segment after 2.0 s was -3.0 m/s instead of +3.0 m/s. Find the ball’s average speed and average velocity in this case.
Questions & Answers
QUESTION:
A ball moves in a straight line (the 𝑥-axis). The graph in Fig. E2.9 shows this ball’s velocity as a function of time. (a) What are the ball’s average speed and average velocity during the first 3.0 s? (b) Suppose that the ball moved in such a way that the graph segment after 2.0 s was -3.0 m/s instead of +3.0 m/s. Find the ball’s average speed and average velocity in this case.
ANSWER:
Solution 9E
Step 1:
a) Average speed, s = Total distance travelled by the object/Total time
In this problem, the velocity of the ball in first two seconds is, v1 = 2 m/s
Therefore, the total distance travelled by the object at first two seconds, d1 = v1t1
d1 = 2 m/s × 2 s = 4 m
The total distance travelled by the object in between 2nd and 3rd second is, d2 = v2t2
d2 = 3 m/s × 1 s = 3 m
Therefore, the total distance travelled by the object, d = d1 + d2 = 4 m + 3 m = 7 m
Total time taken, t = t1 + t2 = 2 s + 1 s = 3 s
Average speed of the ball, s = 7 m / 3 s = 2.33 m/s