Question

Find the average frictional force needed to
stop a car weighing 500 kg in a distance of 25
m if the initial speed is 72 km/h.
ANS: 4000 N​

Answer 1

Answer:

Here Given :-

mass , m= 500 kg

Initial speed u = 75 km/h

 =72000m / 3600 s

u = 20 m/s.

distance,s = 25 m

final speed v = 0

We know the formula

v² - u² =2as

on putting the value

0² - 20² = 2 × a × 25

a= 8 m/s²

but the acceleration is in the opposite direction then

a = -8 m/s²

So Now the frictional force F =  m × a

F = 500 × 8

F = 4000 N.

Hence the frictional force is 4000 N

Explanation: