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