Kinematics: Non-Uniform Motion, Average Speed

Question

A bicyclist travels the first 800 m of a trip at an average speed of 8 m/s, travels the next 550 m in 90 s and the last 75 s at a speed of 21 m/s. Find the average speed of the bicyclist for this trip.

Answer 1

To find the average speed of the bicyclist, find the total distance, the total time, and divide these two values.

Leg 1 Distance = 800m

Leg 1 Time = 800m / 8m/s = 100s

Leg 2 Distance = 550m

Leg 2 Time = 90s

Leg 3 Distance = 21m/s * 75s = 1575m

Leg 3 Time = 75s

Total Distance = 800m+550m+1575m = 2925m

Total Time = 265s

Average Speed = 2925m / 265s = 11.04m/s