a) Elapsed time for trial B: 3.0 s
Explanation:
The elapsed time is defined as the difference between the final time and the initial time:
For trial B, the final time is 4.5 s, while the initial time is 1.5 s, therefore the elapsed time is
b) Average speed for trial B: 1.3 m/s
Explanation:
The average speed is given by the distance traveled divided by the elapsed time:
For trial B, the distance traveled is d=4.0 m, while the elapsed time is t=3.0s, therefore the average speed is