physics college
posted by meera on .
An antelope moving with constant acceleration covers the distance between two points 70.0
m apart in 7.00 s. Its speed as it passes the second point is 15.0 m/s. (a) What is its speed at the first
point? (b) What is its acceleration?
A car is stopped at a traffic light. It then travels along a straight road so that its distance from
the light is given by x(t) = bt2 – ct3, where b = 2.40m/s2 and c = 0.120m/s3. (a) Calculate the average
velocity of the car for the time interval t = 0 to t = 10.0 s. (b) Calculate the instantaneous velocity of the
car at t = 0, t = 5.0 s, and t = 10.0 s. (c) How long after starting from rest is the car again at rest?

ONe question per post, please. I helps you to put down what you think needs to be done, or what you have tried, that way, we can see where your thinking is going askew, and correct that.
avg velocity= (Vf+Vi)/2=distance/time
solve for Vi
Vf=Vi+at solve for a 
Water flows (velocity initial=0) over a dam at the rate of 660 kg/s and falls vertically 81 m before striking the turbine blades. Calculate the rate at which mechanical energy is transfered to the turbine blades, assuming 55% efficiency.