Question

At an accident scene on a level road, investigators measure a car's skid mark to be 98 m long. It was a rainy day and the coefficient of friction was estimated to be 0.38. a) Use these data to determine the speed of the car when the driver slammed on (and locked) the brakes.b) Why does the car's mass not matter?

Answer 1

Answer:

a. V = 19.1m/s

b. The mass of the car does not matter

Explanation:

A.

KE = 1/2mv² = fd --------(1)

Fd = umgd ---------(2)

Therefore,

1/2mv² = umgd ---------(3)

M will cancel itself out from both sides of equation 3.

Then we will have:

1/2v² = ugd

Then we cross multiply to make v² the subject of the formula

V² = 2ugd

V = √2ugd -------(4)

U = 0.38

g = 9.81

d = 98

When we input these values into equation 4, we will have:

V = √2x0.38x9.81x98

V = √730.6488

V = 27.03m/s

B.

The mass of the car does not actually matter as the mass was cancelled out on the both sides of equation 3