The first step is to find the acceleration of the car. We would apply one of Newton's formula of motion which is expressed as
v = u + at
where
v = final velocity
u = initial velocity
a = acceleration
t = time
From the information given,
u = 10
v = 0 because the car came to a stop
t = 2.5
By substituting these values into the formula, we have
0 = 10 + 2.5a
Subtracting 2.5a from both sides of the equation, we have
0 - 2.5a = 10 + 2.5a - 2.5a
- 2.5a = 10
Dividing both sides of the equation by - 2.5, we have
- 2.5a/- 2.5 = 10/- 2.5
a = - 4 m/s^2
The negative sign tells us that the car was decelerating.
The formula for calculating force is expressed as
Force = mass x acceleration
Given that mass = 90 kg,
Force = 90 x 4 = 360
The correct answer is
360 N
