Question

A bowling ball falls freely from rest for 10 seconds before it hits the ground. Neglect air resistance.Is the average speed of the ball during the first 5 seconds greater than, less than, or the same as the average speed of the ball during the last 5 seconds?

Answer 1

Answer:

the average speed of the ball during the first 5 seconds is less than the average speed of the ball during the last 5 seconds

Explanation:

The average speed is defined as

$v_{\text{avg}}=\frac{v_{i1}+v_{f1}}{2}$

where v_i = inital speed and v_f = final speed.

Now for the first five seconds, we know that the ball started from rest; therefore, v_i = 0, and so the average speed is

$v_{\text{avg}}=\frac{0+v_{f1}}{2}$$\boxed{v_{\text{avg}}=\frac{v_{f1}}{2}}$

where v_f = final velocity at the end of the first 5 seconds.

Now the average velocity in the last 5 seconds is

$v_{\text{avg}}=\frac{v_{i2}+v_{f2}}{2}$

Realising that v_i2 = v_f1 ( the initial velocity at the beginning of last 5 seconds = final velocity at the end of first 5 seconds) and that vf_2 > v_i2 gives us

$undefined$