Question

A car going 72.0 km/h (20.0 m/s) slows down to 36.0 km/h (10.0 m/s) in 5.00 seconds. Calculate the acceleration in

m/s^2

Answer 1

`\boxed{\sf Acceleration \ (a) = -2 \ m/s^2}`

Given:

Initial velocity (u) = 20 m/s

Final velocity (v) = 10 m/s

Time taken (t) = 5 seconds

To Find:

Acceleration (a) of the car

Step-by-step explanation:

From equation of motion we have:

`\boxed{ \bold{v = u + at}}`

By substituting value of v, u & t in the equation we get:

`\sf \implies 10 = 20 + 5a \\ \\ \sf \implies 5a + 20 = 10 \\ \\ \sf \implies 5a = 10 - 20 \\ \\ \sf \implies 4a = - 10 \\ \\ \sf \implies a = - (10)/(5) \\ \\ \sf \implies a = - 2 \: m {s}^( - 2)`

`\therefore`

Acceleration (a) of the car = -2 m/s²