# Physics

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 = 2.60 m/s2 and c = 0.150 m/s3.
(a) Calculate the average velocity of the car for the time interval t = 0 to t = 8.0 s.
m/s

(b) Calculate the instantaneous velocity of the car at the following times:
i) t = 0
m/s
ii) t = 4.0 s
m/s
iii) t = 8.0 s
m/s

(c) How long after starting from rest is the car again at rest

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1. a) average velocity= (x(8)-x(0))/8

b) v(t)=x'(t)=2bt-3ct^2

Put t=0;4;8 and calculate. I assume you know calculus to get v(t)=x'(t)

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bobpursley
2. You can do this yourself.

For average velocity, compute
x at 0 and 8 s and divide by the elapsed time, 8s

For instantaneous velocity, take the derivative dx/dt at each of the times listed.

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3. a pendulum has a period on the earth of 1.35s.what is its period on the surface of the moon where g=1.62m/s^2

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