Question

A 1500 kg car skids to a halt on a wet road where μk = 0.47. You may want to review (Pages 141 - 145) . Part A How fast was the car traveling if it leaves 68-m-long skid marks?

Answer 1

The car travels at a speed of 25m/s.

Step-by-step explanation:

Given-

Mass, m = 1500kg

Coefficient of friction, μk = 0.47

Distance, x = 68m

Speed, s = ?

We know,

`Force, F = ma`

and

F = μ X m X g

Therefore,

μ * m * g = m * a

μ * g = a

Let, g = 9.8m/s²

So,

`a = 0.47 * 9.8 m/s^2`

`a = 4.606m/s^2`

We know,

`v^2 - u^2 = 2as`

where, v is the final velocity

u is the initial velocity

a is the acceleration

s is the distance

If the car comes to rest, the final velocity, v becomes 0.

So,

`u^2 = 2 * 4.606 * 68\\\\u^2 = 626.416m/s\\\\u = 25m/s`

The car travels at a speed of 25m/s.