Question

If a car goes from 20 miles per hour to 10 miles per hour in 5 seconds, find its acceleration

Answer 1

A= -2 due to is a desacceleration

Answer 2

`a = -0.89 m/s^2`

Step-by-step explanation:

initial speed of the car is given as

`v_i = 20 miles/hour`

here we know that

`v_i = 20 * (1609)/(3600)`

`v_i = 8.94 m/s`

final speed of the car is given as

`v_f = 10 mile/hour`

`v_f = 10 * (1609)/(3600)`

`v_f = 4.47 m/s`

now we have

`a = (v_f - v_i)/(\Delta t)`

`a = (4.47 - 8.94)/(5)`

`a = -0.89 m/s^2`