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Homework Problems

 

HW#5   Ch 2: Motion Along a Straight Line

1. A baseball is launched vertically with an initial velocity of 20 m/s.  a) How long is the baseball in the air?  b) What is the greatest height reached by the ball?  c) When is the ball 15 m above the ground?

2. An automobile accelerates from rest at 4 m/s2 for 10 seconds. The speed is then held constant for 20 seconds, after which there is an acceleration of −2 m/s2 until the automobile stops. What is the total distance traveled?

3. A metal screw comes loose from underneath an elevator that is moving upward at a speed of 6 m/s. The screw reaches the ground in 3 seconds. a) How high up was the elevator when the screw came loose? b) What is the speed of the screw when it hits the ground?

4. An object is dropped from height D. During the final second of its fall, it drops a distance of 26 m. What was the original height?

5. A projectile is launched downward from the top of a 200 m cliff at an initial velocity of 40 m/s. How long does it take to reach the ground, neglecting air resistance?