Question

If a runner starts at rest and reaches a speed of 20 m/s in 2 second. what is the acceleration?

Answer 1

`10(m)/(s^(2))`

Explanation:

Let u = Initial speed
`((m)/(s))`

v = Final speed
`((m)/(s))`

t = time (seconds)

a = Acceleration

According to this question:

`u= 0 (m)/(s)` (i.e starts at rest)

`v = 20 (m)/(s)`

`t = 20s`

a = ?

`a = (v - u)/(t)`

=
`(20 (m)/(s) - 0(m)/(s))/(2s)`

=
`(20(m)/(s))/(2s)`

Acceleration=
`10(m)/(s^(2) )`

Answer 2

initial speed (u)= 0m/s (at rest)

final speed (v)= 20m/s

time taken (t)= 2seconds

we have,

acceleration;a= (v-u)/t

=(20-0)/2

=10m/s²