Question

The Jamaican bobsled team hit the brakes on their sled so that it decelerates at a uniform rate of 0.43 m/s^2. How long does it take to stop if it travels 85 m before coming to rest

Answer 1

Answer: 19.88 seconds.

Explanation:

For this question we've to make use the consideration of equations of motion. Especially or rather precisely v²- u² = 2as

In this question as the deceleration is given a value will be negative.

Also final velocity will be zero as it finally does comes to rest.

So the equation turns to u²= 2as (even after considering value of a negative)

Deceleration = 0.43 m/s²

As it takes 85 metres to come to rest after brakes applied and deceleration comes into effect distance covered or s will be 85m

√2*0.43*85= u

u= 8.55 m/s

Now for time needed t = u/a as v is zero. As v=u+at

t= 19.88 secs