Chapter 10 Projectile and Satellite Motion
Exercises
5. In front of the Porsche. The crate and the plane have the same horizontal motion. The crate has vertical motion due to g. See figure 10.4 Combined horizontal and vertical motion and imagine the Porsche beside the leg of the table.
6. (a) The observer on the ground will see the parabolic path because the horizontal and vertical motions are combined. (b) From the cargo hole of the plane, the package would stay below the plane until it hits the ground. Both the package and the plane have the same horizontal motion. (c) Relative to the plane, the object will strike the ground below the plane. (d) With air resistance, from the cargo hole of the place, the package will slow and appear to strike behind the plane.
9. (a) Minimum speed is at the top of the trajectory. See figure 10.9. The resultant vector is the sum of the x and y components. The smallest resultant vector is when the y component is zero. (b) The x component remains constant at all points.
10. Refer to your time-velocity-distance free fall table for the distance below a straight-line ideal path. Will all bullets be affected by g the same and fall the same vertical distance in equal times? See figure 10.16 and imagine a bullet rather than a stone.
11. See figure 10.11 for the answer. Which angle would give the greatest hang time?
13. The same logic as you used in #10 above.
14. (a) Yes. (b) Faster velocity the monkey is hit closer to the branch. Slower velocity the monkey is hit closer to the ground. How is it explained. See figure 10.16. Click Here and use the ARCHER to hit the apple.
15. (a) Zero at the top. See figure 10.14. (b) Remember at 45o the initial velocity of 141 m/s is the resultant of two equal components, the x and y components. Read page 185 for the answer to the value of the x and y components. The top of the trajectory the y component becomes zero, but the x component remains the same. What is the value of the x component? No, not zero.
16. Vertical component not the horizontal component affects the height. See Hang Time Revisited on page 191 for the reasons.
17. Same as #16 above. Think about how the horizontal motion affects the hang-time. Hint: In either case, the player jumped 0.6m up.
18. Explain this with two factors: gravitational pull of moon to the earth, and the tangential speed of the moon as it orbits the earth.
19. Hint: velocity is both magnitude and direction. Even with constant magnitude the direction is ever changing. Acceleration is the change in velocity. The direction of acceleration is due to the effect of g. Describe the direction.
Problems
2. Hint: consider the x and y components separately. (a) dy = ½ g * t2 = 4,500 m (b) dx = vx * t = 8400m (c) below the plane.
4. Hints:
 | Use the same equations as #2, |
| Use the vertical distance (dy ) of the trajectory (1.5m minus the height of the can) to solve for time, and |
| Use the time from (dy ) to solve for the horizontal distance (dx ) to the center of the can. |
6. Hints:
| Use the same equations as #2, |
| Use the vertical distance (dy ) of the trajectory (height of the net) to solve for time, and |
| Use the time from (dy ) and the horizontal distance (dx ) of the court (12m) to solve for the horizontal speed. |