Question

If a car moving at 72.0 takes 300 to stop with uniform acceleration after its brakes are applied, how far will it take to stop under the same conditions if its initial velocity is 36.0 ?

Answer 1

i got it wrong

Answer 2

These are my choices 15.0
37.5
75.0
150

Answer 3

But it isn't 150?

Answer 4

no i got it wrong

Answer 5

first, you need to find out how much acceleration (but slowing down, not going faster, so it will be negative) the car has. do this by using the equation vf^2 = vi^2 + 2ax. substitute in what you already know to find the acceleration. vf=0, vi=72, x=300. then use the same equation after solving for "a" to find x. set vf = 0, vi = 36, a = "a" from previous, and solve for x

Answer 6

hint: a = -8.64 from solving the first equation. put it into the second equation to get x = 75

Answer 7

ok thanks