A 910 kg car is traveling along a hwy at 88 km/hr.?

Question

If the driver applies his brakes, comes to rest in a a distance of 70 miles, what average force acted on the car during deceleration?

Can you please give a detailed answer, thanks.

Answer 1

Vi=88km/h=88000m/3600s=24.4m/s

Vf=Vi-a*t --> 0=Vi-a*t --> a*t=Vi

dx=Vi*t-.5*a*t^2 --> dx=Vi*t-.5*(a*t)*t --> dx=Vi*t-.5*Vi*t

solve for t

a=dv/dt

F=m*a