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# Help with this question

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1. A car was travelling at 30m/s. The driver applied the brakes to decelerate the car uniformly in 4.8 s.
Calculate the braking distance?
???
Have no clue
It is involved with other sub questions like
Calculate the deceleration which is, 6.25m/s^2
And the braking force which is 5625N
But how do you work out the braking distance
In the answers, it says the answer is 73m BUT HOW DID THEY GET THAT?!?!
2. (Original post by Sanjith Hegde123)
A car was travelling at 30m/s. The driver applied the brakes to decelerate the car uniformly in 4.8 s.
Calculate the braking distance?
???
Have no clue
It is involved with other sub questions like
Calculate the deceleration which is, 6.25m/s^2
And the braking force which is 5625N
But how do you work out the braking distance
In the answers, it says the answer is 73m BUT HOW DID THEY GET THAT?!?!
This is a question involving constant acceleration.

The acceleration can be calculated using "definition" of acceleration formula, where v = 0

a = (v - u)/t

The braking distance can found using either
s = 1/2(u)t ---- this is area under the v-t graph
or
v2 = u2 + 2as

The braking force can is using F = ma.
3. (Original post by Sanjith Hegde123)
A car was travelling at 30m/s. The driver applied the brakes to decelerate the car uniformly in 4.8 s.
Calculate the braking distance?
???
Have no clue
It is involved with other sub questions like
Calculate the deceleration which is, 6.25m/s^2
And the braking force which is 5625N
But how do you work out the braking distance
In the answers, it says the answer is 73m BUT HOW DID THEY GET THAT?!?!
Do a=(v-u)/t to get the deceleration and then use s=ut+1/2at^2 to get the displacement.

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