A car starts from rest and travels for 5.2 s with a uniform acceleration of +1.6 m/s2. The driver then applies the brakes, causing a uniform acceleration of -2.1 m/s2. The breaks are applied for 1.50 s.

Question

(a) How far has the car gone from its start?

Answer 1

speed when brakes applied ... 5.2 s * 1.6 m/s^2 = 8.3 m/s

speed after braking ... 8.3 m/s + (1.50 s * -2.1 m/s^2) = 5.2 m/s

use the times and average speeds over the two segments
... to find the distance traveled

Answer 2

Thank you, but I tried doing that and got an answer of 90.45 and said that was wrong... I'm not sure what I'm doing wrong.

Answer 3

check your math

the car is moving for a total of 6.7 s ... 90.45 is too high

also, watch the sig figs ... probably a max of one decimal place in the answer