Question

An athlete takes 2.0 s to reach his maximum speed of 18.0 km/h. What is the magnitude of this average acceleration.

Answer 1

Explanation:

1)convert given velocity in terms of m/s

2)we know that avg.acceleration=change in velocity/time taken

Answer 2

The magnitude of this average acceleration is 2.5 m/s².

Explanation:

Given :

An athlete takes 2.0 s to reach his maximum speed of 18.0 km/h

Here,      u is Initial velocity  

              v is the final velocity  

Initial velocity =  0 m/s

Final velocity = v =18 km/hr  $=18 \times \frac{5}{18}$   =  5 m/s

Time = 2 sec

Average acceleration = a = ?

Formula to be used :  $a=v-\frac{u}{t}$

                                   $a=5-\frac{0}{2}$

                                      $=2.5 \mathrm{m} / \mathrm{s}^{2}$

∴ Magnitude of this average acceleration is 2.5m/s².