Question

A speed truck locks it’s brakes and it skids to a stop. If the truck’s total mass were doubled, it’s skidding distance would be?

Answer 1

Answer:

The skidding distance would be doubled

Explanation:

When the truck applies the brakes and slows down, its motion is a uniformly accelerated motion, so its skidding distance can be found by using the suvat equation

$v^2-u^2=2as$

where

v = 0 is the final velocity (zero since the truck comes to a stop)

u is the initial velocity

a is the acceleration

s is the skidding distance

The acceleration can also be written as

$a=\frac{F}{m}$

where F is the force applied by the brakes and m the mass of the truck. Substituting into the previous equation,

$-u^2 = 2\frac{F}{m}s\\s = -\frac{mu^2}{2F}$

We see that the skidding distance is proportional to the mass: therefore, if the mass of the truck is doubled, the skidding distance will double as well.