Honors PhysicsMotion in 2 Dimensions A

Projectile Motion*

1. MC If air resistance is neglected, the motion of an object projected at an angle consists of a uniform downward acceleration combined with (a) an equal horizontal acceleration, (b) a uniform horizontal velocity, (c) a constant upward velocity, (d) an acceleration that is always perpendicular to the path of motion.  

2. MC A football is thrown on a long pass. Compared to the ball’s initial horizontal velocity, the horizontal component of its velocity at the highest point is (a) greater, (b) less, (c) the same.  

3. MC A football is thrown on a long pass. Compared to the ball’s initial vertical velocity, the vertical component of its velocity at the highest point is (a) greater, (b) less, (c) the same.  

4. CQ A golf ball is hit on a level fairway. When it lands, its velocity vector has rotated through an angle of 90°. What was the launch angle of the golf ball? [Hint: See Fig. 3.11.]  

4. CQ Figure 3.10b shows a multiflash photograph of one ball dropping from rest and, at the same time, another ball projected horizontally at the same height. The two balls hit the ground at the same time. Why? Explain.  

5. CQ In Fig. 3.30, a spring-loaded “cannon” on a wheeled car fires a metal ball vertically. The car is given a push and set in motion horizontally with constant velocity. A pin is pulled with a string to launch the ball, which travels upward and then falls back into the moving cannon every time. Why does the ball always fall back into the cannon? Explain

6. A ball with a horizontal speed of rolls off a bench 2.0 m high. (a) How long will the ball take to reach the floor? (b) How far from a point on the floor directly below the edge of the bench will the ball land?  (a) 0.64 s (b) 0.64 m

7. An electron is ejected horizontally at a speed of from the electron gun of a computer monitor. If the viewing screen is 35 cm from the end of the gun, how far will the electron travel in the vertical direction before hitting the screen? Based on your answer, do you think designers need to worry about this gravitational effect?   no

8. A ball rolls horizontally with a speed of off the edge of a tall platform. If the ball lands 8.7 m from the point on the ground directly below the edge of the platform, what is the height of the platform?  6.4 m

9. A ball is thrown horizontally, with a speed of from the top of a 6.0-m-tall hill. How far from the point on the ground directly below the launch point does the ball strike the ground?  17 m

10. If Exercise 64 were to take place on the surface of the Moon, where the acceleration due to gravity is

only what would be the answer?  40 m11. A pitcher throws a fastball horizontally at a speed of toward home plate, 18.4 m away. (a) If

the batter’s combined reaction and swing times total 0.350 s, how long can the batter watch the ball after it has left the pitcher’s hand before swinging? (b) In traveling to the plate, how far does the ball drop from its original horizontal line?  (a) 0.123 s (b) 1.10 m

12. IE Ball A rolls at a constant speed of on a table 0.95 m above the floor, and ball B rolls on the floor directly under the first ball and with the same speed and direction. (a) When ball A rolls off the table and hits the floor, (1) ball B is ahead of ball A, (2) ball B collides with ball A, (3) ball A is ahead of ball B. Why? (b) When ball A hits the floor, how far from the point directly below the edge of the table will each ball be?  (a) (2) ball B collides with ball A (b) 0.11 m, 0.11 m

** Assume angels to be exact for significant figure purposes.

WILSON PAGE P. 98 # 55-67