A car is travelling at 40m/s^-1. The driver sees emergency ahead and 0.50 seconds later, slams on the brakes.*

Question

The acceleration of the car is -4m/s^-2.

a) what distance does the car travel before the driver slams on the brakes?

Thats all!

I think the answer is 20m but i m not sure!

Answer 1

I would have said 20m but then I saw the acceleration of -4m/s...

So... car initially travelling at 40m/s, in another half a second with a -4m/s acceleration it is travelling at 42m/s. Which means the average speed over that half second is 41m/s - giving a distance travelled of 20.5 metres.

I'm fairly sure 20.5 metres is the correct answer.