Physics: Free fall and Projectile Motion
Free fall characteristics
-acceleration of 9.8m/s/s -experiences no air resistance -undergoes downward acceleration
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.)
0.5 seconds
A ball is thrown upward from the ground with a speed of 20 m/s. Approximately how much time does it take for the ball to reach its highest point?
2 seconds
A ball that is thrown upwards from the ground will eventually reach its highest point (the peak) and fall back to the ground. It takes 3.0 seconds for the ball to reach its highest point. How much time does it take the ball to fall from its peak to the ground? Assume a free fall motion.
3 seconds
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?
75 degrees
A basketball is shot. After the ball leaves the player's hand, in which direction does the ball accelerate?
Always downward
At what point in its path is the vertical component of the velocity (vy) of a projectile at angle the smallest?
At the top
A ball is projected horizontally from the top of a cliff and free falls to the ground. Which one of the following statements regarding the ball's motion is correct?
Falls with constant acceleration
An object that is thrown upward would not be in a free fall state immediately after release.
False
Heavier objects free-fall faster than lighter objects because of ____.
False, all fall at the same rate
Two balls roll off the table at the same time and free fall to the ground. Ball A is moving at 1 m/s when it rolls off the table. Ball B is moving at 2 m/s when it rolls off the table. Which ball has the greatest acceleration as it falls to the ground?
Have same acceleration
At what point in its path is the horizontal component of the velocity (vx) of a projectile the smallest?
It is always the same
A ball that is thrown upwards from the ground will eventually reach its highest point and fall back to the ground. How does its initial speed (when launched from the ground) compare to its final speed (when it lands on the ground)? Assume a free fall motion.
Its initial speed is equal to its final speed.
A ball is dropped from the ceiling and free falls to the floor. Which one of the following statements regarding the ball's motion is incorrect?
The acceleration of the ball increases as it falls to the ground.
A 5-kg iron ball and a 10-kg iron ball are dropped from rest. If we do not take into account air resistance, the acceleration of the heavier ball will be
The same
Which of the following statements are true of the vertical motion of an angle-launched projectile? Select all that apply.
The vertical velocity at the peak of the trajectory is 0 m/s. The vertical velocity decreases as the projectile rises upward toward the peak
Two balls roll off the table at the same time and free fall to the ground. Ball A is moving at 1 m/s when it rolls off the table. Ball B is moving at 2 m/s when it rolls off the table. Which ball hits the ground first?
They land at the same time
Which of the following statements are true of projectiles during their flight? Select all that apply.
Vertical acceleration is downwards, vertical velocity is 0 at peak, horizontal velocity stays the same
An angle-launched projectile travels upward and rightward towards the peak of its trajectory and then falls downward. Which of the following statements are true of the projectile at the moment it is at the peak of its trajectory?
Vertical velocity is 0 m/s
The force of gravity always causes a projectile to ______.
accelerate downward
Free falling object
an object that is falling under the sole influence of gravity
A ball tossed vertically upward rise, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always
directed downward
A downward falling parachutist pulls the chord and rapidly slows down. The velocity direction is _____ and the acceleration direction is _____.
down, up
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 _______.
hotizontal
A tennis ball is hit horizontally from a height of 1-meter above the ground. After being hit, it moves as a projectile. The magnitude of the vertical velocity of the ball while in flight will _____.
increase at a constant rate
Which of the following statements are true of all free-falling objects?
mass doesn't affect free falls, gravity is only force ating on object
A softball is thrown at an angle to the horizontal. As the softball moves upward toward the peak of its trajectory, it ________. As the softball falls downward from the peak of its trajectory, it _________.
slows down, speeds up
Suppose that a ball is thrown straight upward and that air resistance has no appreciable effect upon its motion. As the ball rises towards its peak, its velocity vector is directed ____ and its acceleration vector is directed ____. Which two words fill in these two blanks in their respective order?
upward, downward
Which of the following statements are true of the horizontal motion of an angle-launched projectile? Select all that apply.
velocity at peak is same as when launched, horizontal acceleration is 0m/s/s
Suppose that a ball is thrown straight upward and that air resistance has no appreciable effect upon its motion. At the instant in time that the ball is at the peak of its trajectory, the _____. Selected:
velocity is 0.0 m/s and the acceleration is approximately 10 m/s/s
