An automobile has a mass of 2100 kg and a velocity of +17 m/s. it makes a rear-end collision with a stationary car whose mass is 1900 kg. the cars lock bumpers and skid off together with the wheels locked. (a) what is the velocity of the two cars just after the collision? (b) find the impulse (magnitude and direction) that acts on the skidding cars from just after the collision until they come to a halt. (c) review: if the coefficient of kinetic friction between the wheels of the cars and the pavement is μk = 0.68, determine how far the cars skid before coming to rest.

a.

b.

c.

Explanation:

a.

Velocity of the two cars just after the collision:

Using the law of conservation of

b.

Frictional force acting on the combined mass of cars:

where:

N = reaction normal to the contact surface by the ground

is the resistance force to the motion of the wheels

Now, by Newton's second law of motion:

Now impulse is the impact load acting acting for certain time:

c.

The distance the the cars skid before coming to rest:

using equation of motion:

we've since final velocity is zero

now since we have:

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.