FA #19 - Characteristics of Projectiles
5. An object is undergoing free fall motion. As it falls, the object's ____. a. speed increases b. acceleration increases c. both of these d. none of these
a
7. A football is kicked into the air at an angle of 45 degrees with the horizontal. At the very top of the ball's path, its acceleration is _______. (Neglect the effects of air resistance.) a. entirely vertical b. entirely horizontal c. both vertical and horizontal d. not enough information given to know.
a
8. A football is kicked into the air at an angle of 45 degrees with the horizontal. At the very top of the ball's path, the net force acting upon it is _______. (Neglect the effects of air resistance.) a. entirely vertical b. entirely horizontal c. both vertical and horizontal d. not enough information given to know.
a
Two projectiles are fired at equal speeds but different angles. one is fired at an angle of 30 degrees and the other at 60 degrees. The projectile to his the ground first will be the one fired at ____. (assume no air resistance) a. 30 degrees b. 60 degrees c. both hit at the same time
a
11. Roll a bowling ball off the edge of a table. As it falls, its horizontal component of velocity ___. a. decreases b. remains constant c. increases
b
6. A football is kicked into the air at an angle of 45 degrees with the horizontal. At the very top of the ball's path, its velocity is _______. a. entirely vertical b. entirely horizontal c. both vertical and horizontal d. not enough information given to know.
b
10. At what point in its path is the vertical component of the velocity (vy) of a projectile the smallest? a. The instant it is thrown. b. Halfway to the top. c. At the top. d. As it nears the top. e. It is the same throughout the path.
c
12. A bullet is fired horizontally and hits the ground in 0.5 seconds. If it had been fired with twice the speed in the same direction, it would have hit the ground in ____. (Assume no air resistance.) a. less than 0.5 s. b. more than 0.5 s. c. 0.5 s.
c
13. A projectile is launched at an angle of 15 degrees above the horizontal and lands down range. For the same speed, what other projection angle would produce the same downrange distance? a. 30 degrees. b. 45 degrees. c. 50 degrees. d. 75 degrees e. 90 degrees.
d
9. At what point in its path is the horizontal component of the velocity (vx) of a projectile the smallest? a. The instant it is thrown. b. Halfway to the top. c. At the top. d. As it nears the top. e. It is the same throughout the path.
e
3p. T or F:Consider a projectile launched from ground level at a fixed launch speed and a variable angle and landing at ground level. The vertical displacement of the projectile during the first half of its trajectory (i.e., the peak height) will always increase as the angle of launch is increased from 0 degrees to 90 degrees.
False
4a. T or F:The time that a projectile is in the air is dependent upon the horizontal component of the initial velocity.
False
4e. T or F:Assume that a kicked ball in football is a projectile. If the ball takes 3 seconds to rise to the peak of its trajectory, then it will take 6 seconds to fall from the peak of its trajectory to the ground.
False
1c. T or F: A projectile must be moving in the downward direction.
False
2a. T or F:A projectile does not have a horizontal velocity.
False
2b. T or F:A projectile with a rightward component of motion will have a rightward component of acceleration.
False
2c. T or F:The horizontal velocity of a projectile changes by 9.8 m/s each second.
False
2e. T or F:The horizontal velocity of a projectile is 0 m/s at the peak of its trajectory.
False
2i. T or F:As a projectile rises towards the peak of its trajectory, the horizontal velocity will decrease; as it falls from the peak of its trajectory, its horizontal velocity will decrease.
False
2j. T or F:Consider a projectile launched from ground level at a fixed launch speed and a variable angle and landing at ground level. The horizontal displacement (i.e., the range) of the projectile will always increase as the angle of launch is increased from 0 degrees to 90 degrees.
False
3a. T or F:The vertical component of a projectile's velocity is a constant value of 9.8 m/s.
False
3b. T or F:The vertical component of a projectile's velocity is constant.
False
3e. T or F:A projectile with an upward component of motion will have a upward component of acceleration.
False
3j. T or F:The final vertical velocity of a projectile is always equal to the initial vertical velocity.
False
3k. T or F:The vertical acceleration of a projectile is 0 m/s/s when it is at the peak of its trajectory.
False
3l. T or F:As a projectile rises towards the peak of its trajectory, the vertical acceleration will decrease; as it falls from the peak of its trajectory, its vertical acceleration will decrease.
False
3m. T or F:As a projectile rises towards the peak of its trajectory, the vertical acceleration is directed upward; as it falls from the peak of its trajectory, its vertical acceleration is directed downward.
False
3o. T or F:As a projectile rises towards the peak of its trajectory, the vertical velocity will decrease; as it falls from the peak of its trajectory, its vertical velocity will decrease.
False
1a. T or F: A projectile is a free-falling object.
True
1b. T or F: A projectile experiences negligible or no air resistance.
True
1d. T or F: A projectile must be accelerating in the downward direction.
True
1e. T or F: A projectile does not have to have horizontal motion.
True
1f. T or F: A projectile could begin its projectile motion with a downward velocity.
True
1g. T or F: A projectile does not need to be "falling."
True
2d. T or F:A projectile with a horizontal component of motion will have a constant horizontal velocity.
True
2f. T or F:The horizontal velocity of a projectile is unaffected by the vertical velocity; these two components of motion are independent of each other.
True
2g. T or F:The horizontal displacement of a projectile is dependent upon the time of flight and the initial horizontal velocity.
True
2h. T or F:The final horizontal velocity of a projectile is always equal to the initial horizontal velocity.
True
2k. T or F:Consider a projectile launched from ground level at a fixed launch angle and a variable launch speed and landing at ground level. The horizontal displacement (i.e., the range) of the projectile will always increase as the launch speed is increased.
True
3c. T or F:The vertical component of a projectile's velocity is changing.
True
3d. T or F:The vertical component of a projectile's velocity is changing at a constant rate.
True
3f. T or F:A projectile with an downward component of motion will have a downward component of acceleration.
True
3g. T or F:The magnitude of the vertical velocity of a projectile changes by 9.8 m/s each second.
True
3h. T or F:The vertical velocity of a projectile is 0 m/s at the peak of its trajectory.
True
3i. T or F:The vertical velocity of a projectile is unaffected by the horizontal velocity; these two components of motion are independent of each other.
True
3n. T or F:The peak height to which a projectile rises above the launch location is dependent upon the initial vertical velocity.
True
3q. T or F:Consider a projectile launched from ground level at a fixed launch angle and a variable launch speed and landing at ground level. The vertical displacement of the projectile during the first half of its trajectory (i.e., the peak height) will always increase as the launch speed is increased.
True
4b. T or F:The time that a projectile is in the air is dependent upon the vertical component of the initial velocity.
True
4c. T or F:For a projectile which lands at the same height that it is projected from, the time to rise to the peak is equal to the time to fall from its peak to the original height.
True
4d. T or F:For the same upward launch angles, projectiles will stay in the air longer if the initial velocity is increased.
True
