Question

consider a car moving along a straight horizontal road with a speed of 72km/h If the coefficient of static friction between tyres and road is0.5 the shortest distance in which the car can be stopped

Answer 1

Given the coefficient of static friction, we can get the acceleration.

Acceleration = ∞g

Where ∞ = coefficient of friction

g = acceleration due to gravity = 10

acceleration = 10 × 0.5 = 5

Given that the car comes to rest, the acceleration is negative.

a = - 5m/s²

Lets convert the speed to meters per second as follows :

72 × 5/18 = 20m/s

u = initial velocity = 20

v = 0 m/s

We can use the following kinematics equation :

v² = u² - 2as

0 = 20² - 2 × 5 × s

0 = 400 - 10s

10s = 400

s = 400/10

s = 40 m

The distance equals 40 m.

Answer 2

this is a very easy question.... u just need to catch the concept..... to find the shortest distance... we need acceleration.... and by considering kinetic friction we can solve the problem very easily

plz... refer to the attachment

hope it helps