Question

An aircraft lands and brakes, slowing from 250 m/s to 5 m/s in 30 secs. What is its acceleration?

Answer 1

`8.17" m s"^-2`

Explanation:

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

`a` is acceleration
`v` is final velocity
`u` is intial velocity
`t` is time.

`a=(5-250)/30`
`=-245/30`
`=-49/6" m s"^-2`
`~~8.17" m s"^-2`

Answer 2

`-8.16` `ms^-2`

Explanation:

To solve this, we use the formula

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

Where, `a` is the acceleration, `v` is the final and `u` the initial velocities.And, `t` is the time taken

So, here, initial velocity is `250m/s` and final velocity is `5m/s` and the time taken is `30s`

`rarra=(5-250)/30` `ms^-2`

`rarra=-245/30ms^-2`

`rarra=-49/6ms^-2`

`color(green)(rArra~~-8.16` `color(green)(ms^-2`

Note: here the value is negative, so the plane is decelerating(opposite of accelerating). So, this is known as deceleration.

Hope that helps...`phi`