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

Answer:

$a = -0.89 m/s^2$

Explanation:

initial speed of the car is given as

$v_i = 20 miles/hour$

here we know that

$v_i = 20 \times \frac{1609}{3600}$

$v_i = 8.94 m/s$

final speed of the car is given as

$v_f = 10 mile/hour$

$v_f = 10 \times \frac{1609}{3600}$

$v_f = 4.47 m/s$

now we have

$a = \frac{v_f - v_i}{\Delta t}$

$a = \frac{4.47 - 8.94}{5}$

$a = -0.89 m/s^2$