Question

A 1500 kg car traveling​ at 35 m/s hits its brakes and comes to rest in 5 seconds. Calculate the force applied by the brakes. (hint: solve for a first) Show all steps!!

Answer 1

We are given:

m = 1500 kg

initial velocity (u) = 35 m/s

final velocity (v) = 0 m/s

time (t) = 5 seconds

acceleration = a m/s/s

Force (f) = F newtons

Solving for acceleration:

Using the first equation of motion:

v = u + at

replacing the variables

0 = 35 + a(5)

a = -35/5

a = -7 m/s/s

Force applied by the brakes:

From newton's second law of motion:

F = ma

replacing the variables

F = (1500)(-7)

F = -10500 N

Therefore, the force applied by the brakes is -10500 N, we have a negative sign since the force is being applied opposite to the direction of motion