Question

A car has a weight of 25000 N and its brakes can apply a maximum force of 628 N to stop it. The car is initially moving at a speed of 6.5 m/s and comes to a complete stop.
How much time will it take for the car to stop?

Answer 1

Time required : 25.876 s

Further explanation

Given

A car weight = 25000 N

Brake force = 628 N

vo= 6.5 m/s

vt = 0(stop)

Required

time to stop

Solution

W = m . g

25000 = m.10

m=2500 kg

Newton's second law

F = m . a

628 = 2500 . a

$\tt a=\dfrac{628}{2500}=0.2512~m/s^2$

vt=vo-at(deceleration a=-)

0=6.5-0.2512.t

0.2512.t=6.5

t=25.876 s