Question

An 1100-kg car traveling at 27.0 m/s starts to slow down and comes to a complete stop in 578 m. What is the magnitude of the average braking force acting on the car? [Hint: Use appropriate kinematic equation to find a, and then use Newton’s second law]

Answer 1

Answer:

693.685 N

Explanation:

t = Time taken

u = Initial velocity = 27 m/s

v = Final velocity

s = Displacement = 578 m

a = Acceleration

m = Mass

Equation of motion

$v^2-u^2=2as\\\Rightarrow a=\frac{v^2-u^2}{2s}\\\Rightarrow a=\frac{0^2-27^2}{2\times 578}\\\Rightarrow a=-0.63062\ m/s^2$

Force

F = ma

$F=1100\times -0.63062\\\Rightarrow F=-693.6851\ N$

Magnitude of braking force required to stop the car is 693.685 N