Need help on these problems:
1. You are driving at night on a highway at a speed of 18.2m/s. All of a sudden you see a deer in the road 38 m ahead.
a. If you can slow down at a maximum rate of 4.50 m/s2, what reaction time is required to avoid hitting the deer?
i keep getting 4.044 sec but its saying that answer is incorrect...
2. An Olympic sprinter competes in 100m dash. The runner accelerates from rest to maximum speed at a constant rate during the first 3s, and completes the race in 10.29s.
a. What are the accelerations and maximum speed of the sprinter?
_______ m/s2
_______ m/s
b. The sprinter wants to estimate the time to run a 200m dash. Assuming the same acceleration and maximum speed as in part (a), determine the time required to complete the race. The present world record (as of 2013) is 19.19s. THINK ABOUT IT:Do the assumptions made for this race seem plausible?
_______ s
3. A speeding car is traveling at a constant speed of 39m/s. A police car starts from rest just as the speeder passes it, and accelerates at a constant rate of 2.2m/s2. The maximum speed of the police car is 53.3m/s. Once the police car reaches maximum speed, it travels at a constant speed.
a. How long does the police car take to catch the speeder? s
b. How far has each vehicle traveled? m
c. If the police car starts 1.1s after the speeder passes it, how long does it take to catch the speeder? s
i got 20s for a which also says incorrect and 160 for b which says incorrect...
This post was edited by OrganicGreens on Sep 13 2014 01:27pm