Question

an athlete starting from rest picks up a speed of 10m/s over a distance of 100m. find the acceleration and the time in which he completes the race.​

Answer 1

Refer to the attachment please

Answer 2

• initial velocity=u=0m/s
• Final velocity=v=10m/s
• Distance=s=100m

We don't have time taken by the athlete .Hence we can't use first or second equation of kinematics .

According to third equation of kinematics

$\boxed{\sf v^2-u^2=2as}$

• a stands for acceleration

$\\ \sf\longmapsto 10^2-0^2=2a(100)$

$\\ \sf\longmapsto 100=200a$

$\\ \sf\longmapsto a=\dfrac{100}{200}$

$\\ \sf\longmapsto a=0.5m/s^2$

Now we know

$\boxed{\sf Acceleration (a)=\dfrac{v-u}{t}}$

$\\ \sf\longmapsto t=\dfrac{v-u}{a}$

$\\ \sf\longmapsto t=\dfrac{10-0}{0.5}$

$\\ \sf\longmapsto t=\dfrac{10}{0.5}$

$\\ \sf\longmapsto t=20s$

Thank u