4. As an object moves with constant acceleration. At t=0 the position is x=0. At

Question

4. As an object moves with constant acceleration. At t=0 the position is x=0. At t=1 the position is x=1 and at t=2 the position is x=5. What is the acceleration? What is the velocity at t=0? What is the average velocity in the first 1.5 seconds?

6.A speeder is driving with constant velocity at 20m/s. She approches a police car. As soon as she passes by, the police car (Which was at rest) accelerates with constant acceleration 5 m/s^2. How long does it take him to catch her?

1. A car is driving at a constant speed of 50km/hr. Another car starts from the same position after 20 seconds. The two cars meet after 5km from the original position. Represent this problem graphically, position versus time. How long does the second car have to drive to reach the first car? What is the velocity of the second car?

Explanation / Answer

4. for t =1

x = ut + at^2/2

1 = u + 0.5a

for t = 2

5 = 2u + 2a

on solving both

a = 3 m/s2

and

velocity at t =0 , u (0) = -0.5m/s

averrage = x(1.5) - x(0) / 1.5 = [-0.5x1.5 + 3x1.5^2 /2 ]/1.5 = 1.75 m/s

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