Question

A bicyclist and a runner are waiting at a red light. When the light turns green they start to speed up and the bicyclist gets to a final speed of 20 mph in 5 seconds. The runner gets to a final speed of 11 mph in 3 seconds. Which one had the greater acceleration?
the bicyclist or the runner.

Answer 1

Answer:

The acceleration of bicyclist is greater than that of the runner.

Explanation:

It is given that,

Initial speed of both bicyclist and a runner is 0 as they both are waiting at a red light,

When the light turns green they start to speed up.

Final speed of the bicyclist is 20 mph in 5 seconds

The runner gets to a final speed of 11 mph in 3 seconds.

20 mph = 8.94 m/s

11 mph = 4.91 m/s

Acceleration of bicyclist is :

$a_b=\dfrac{v}{t}\\\\a_b=\dfrac{8.94\ m/s}{5\ s}\\\\a_b=1.78\ m/s^2$

Acceleration of runner is :

$a_r=\dfrac{v}{t}\\\\a_r=\dfrac{4.91\ m/s}{3\ s}\\\\a_r=1.63\ m/s^2$

It is clear that the acceleration of bicyclist is greater than that of the runner.