Question

A car of mass 1200 kg traveling westward at 30. m/s is slowed to a stop in a distance of 50. m by the car’s brakes. What was the braking force? Select one:
A. 1,800,000 N B. 0.80 N C. 11,000 N D. 2000 N

Answer 1

I believe that the answer is C. 11,000

Answer 2

Answer:

C. 11000 N

Explanation:

car kinematics :The car moves with uniformly accelerated movement for this movement the following formula apply:

vf²= v₀² + 2* a*d  Formula (1)

vf : final speed (m/s)

v₀ : initial speed (m/s)

a  : acceleration (m/s²)

d  : distance (m)

Car kinetics:  We apply Newton's second law:

∑F= m*a

∑F : Algebraic sum of forces (N)

m : mass (kg)

a  : acceleration (m/s²)

Acceleration Calculation

We replace Vf=0 , v₀= 30 m/s , d=50m  the  formula (1)

0= 30²+ 2*a*50

a= - 30² /2*50 = - 900/100 = -9 m/s²

Braking force Calculation

∑F= m*a

-F =  1200 kg*(-9 m/s²)

F = 10800N