Projectile practice quiz SOLUTIONS

1. The free-body diagram of a projectile shows what forces are acting on the projectile. If air resistance is ignored, what other forces is acting on the projectile? Only the force of the object’s weight is being applied.

2. The path of a projectile is called __________ Trajectory is the path of all projectile object. In the absent of air, projectile’s trajectory is parabolic.

3. In an effort to create a cannonball-style splash, eight-year old Matthew runs off the edge of the board of the high dive at 4.6 m/s and falls 2.3 m to the water below. Determine the time for Matthew to fall the 2.3 m to the water. Use the shortcut formula to get the time.

4. In an effort to create a cannonball-style splash, eight-year old Matthew runs off the edge of the board of the high dive at 4.6 m/s and falls 2.3 m to the water below. What horizontal distance from the edge of the board will Matthew plunge into the water?

5. In an effort to create a cannonball-style splash, eight-year old Matthew runs off the edge of the board of the high dive at 4.6 m/s and falls 2.3 m to the water below. With what speed does Matthew enter the water? To solve for the speed, we need both the horizontal and the vertical velocity. vf = vi + at = (-9.8)(0.685) = -6.71 m/s 4.6 m/s V = ? 6.71 m/s

6. Li Ping Phar, the famous Chinese ski jumper, leaves the ramp with an initial velocity of 34.9 m/s at an angle of 35° (horizontal velocity of 28.59 m/s and vertical velocity of 20.02 m/s) Determine the total time of flight. To determine the flight time, we need to solve for the time the skier peaked and came back down. Peak time: vf = vi + at 0 = 20.02 + (-9.8)t t = -20.02/-9.8 = 2.04 s Total time: 2t = 2(2.04) = 4.08 seconds

7. Li Ping Phar, the famous Chinese ski jumper, leaves the ramp with an initial velocity of 34.9 m/s at an angle of 35° (horizontal velocity of 28.59 m/s and vertical velocity of 20.02 m/s) Determine the horizontal displacement. x = vx t x = (28.59)(4.08) = 117 m

8. Li Ping Phar, the famous Chinese ski jumper, leaves the ramp with an initial velocity of 34.9 m/s at an angle of 35° (horizontal velocity of 28.59 m/s and vertical velocity of 20.02 m/s) Determine the peak height (relative to the starting height). Assume that Li lands at the same height as the top of the ramp and that Li is a projectile. d = vit + ½ at2 d = ½ at2 d = ½ (-9.8)(2.04)2 = 20.45 m

9. For 9 and 10. A cargo plane is dropping aide to a local village without the use of a parachute. If the plane is flying horizontally with a velocity of 100 m/s and an altitude of 200 m, determine the time it would take the cargo to hit the open field below.

10. For 9 and 10. A cargo plane is dropping aide to a local village without the use of a parachute. If the plane is flying horizontally with a velocity of 100 m/s and an altitude of 200 m, How far from the field should the airplane release its cargo? (horizontal displacement)

11. One of the groups in class did the BOWSTRIKE activity and they measured an average of 0.38 m drop from the intended target on the whiteboard. They were standing 5.5 meters from the whiteboard. Determine their horizontal velocity. to solve for the horizontal velocity, we need to find the time it takes for the dart to drop 0.38 m

12. You throw a stone horizontally at a speed of 5.0 m/s from the top of a cliff that is 78.4 m high. How long does it take the stone to reach the bottom of the cliff?

13. You throw a stone horizontally at a speed of 5.0 m/s from the top of a cliff that is 78.4 m high. How far from the base of the cliff does the stone hit the ground?

14. You throw a stone horizontally at a speed of 5.0 m/s from the top of a cliff that is 78.4 m high. What is the actual velocity of the stone just before it hits the ground? vf = vi + at = (-9.8)(4) = -39.2 m/s 5 m/s V = ? 39.2 m/s