# Physics homework

1.A car drives north. At t-0, it passes a road sign. The distance north of the sign is given by

a. Find the expression for the car’s instantaneous velocity as a function of time.

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Order Paper Nowb. Find the expression for the car’s acceleration as function of time. Does the car experience constant acceleration?

c. Find the average velocity between t=1s and t=3s.

d. What is the car’s instantaneous velocity at t=1s?

e. What is the cars instantaneous velocity and acceleration at t=3s?

2. A motor cyclist has constant acceleration of 4 m/s2. At t=0, he is 5m east of a road sign and is traveling east at 15 m/s.

a. We want to find his position a t=2.0 s. First, choose an origin for your coordinate system, and identify the initial and final states. Also write down the initial and final quantities.

b. Choose a constant acceleration equation which includes your desired quantity as the only unknown (if possible). In this case the unknown is the position at t=2s, solve for this position.

c. Follow the same procedures to find the velocity at t = 2 s.

d. Follow the same procedures to find the position when the motorcycle has a velocity of 25 m/s

3. A car traveling at 15 m/s passes a police car. At that instant, the police car accelerates at a constant rate of 3 m/s2 in pursuit. We wish to find how much time elapses before the officer catches the car.

a. Choose a coordinate system for this problem and identify the initial states starting when the car passes the police.

b. Define the final state or conditions which enables you to answer the above question.

c. To solve this problem identify the two equations (one for each vehicle) which satisfy part b. Solve for the unknown time.

4. A ball is thrown straight up in the air leaving your hand 1 m from the ground, with an initial velocity of 8 m/s.

a. Choose a coordinate system for this problem.

b. Is this a constant acceleration problem.

c. Find the time it takes to reach the maximum height.

d. Find the maximum height obtained by the ball.

e. Find the time to reach the ground.

f. Find the velocity when the ball hits the ground.

5. A ball is thrown at 25 m/s at an angle of 250 above the horizontal.

a. Choose a coordinate system and sketch the motion of the ball.

b. Find the initial velocity of the ball in the x and y directions.

c. Find when the ball reaches its highest point.

d. Find how long it takes to return to the ground.

e. How far did the ball go the x direction.

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