5.3. Practice Sets: Free Fall
Chapter Equations
Try It!
- A basketball player throws a ball upward from
above the floor; the ball is caught by another player on its way back down, at above the floor. Which of the following statements are true:- The time the ball travels upward is greater than the time it travels downward.
- The time the ball travels upward is equal to the time it travels downward.
- The time the ball travels upward is less than the time it travels downward.
- A child drops a toy from a bridge into the water below. This is a free-fall motion described by the following (choose the correct statement):
- The final velocity is zero.
- The initial velocity is zero.
- The motion is a decelerated motion (negative
). - This is a uniform motion.
- A student throws a book upward from floor level. The book’s round trip takes
Which of the following statements are true:- The initial throwing velocity cannot be calculated (there is not enough information).
- The time the book took to reach the maximum height is not known.
- The time the book took to reach the floor (on its way down) is
.
Practice
- A ball is being thrown upwards with a velocity of
. Find:- The maximum height the ball can reach;
- The time needed for the ball to reach the maximum height;
- The time the ball was in flight assuming it is coming back to the same level.
Answer:
- A person throws a ball up in the air from the top of a
high building. Knowing that the ball goes up in the air for (from the throwing point), find:- The velocity of the ball at the moment it was thrown;
- The velocity of the ball when it reaches the ground;
- The time it takes the ball to reach the ground.
Answer:
- A book is being dropped from the top of a
high flight of stairs. Find:- The velocity of the book when it reaches the ground;
- The time needed for the book to reach the ground.
Answer:
- A child throws a rock from a bridge with a velocity of
. Given that it takes the rock to reach the water underneath the bridge, how far down is the surface of the water?
Answer:
Challenge Question(s)
An elephant taking a bath in a river is sucking water into its trunk. Suddenly, the passage of water is blocked by a rock. The elephant then turns its trunk upward and blows the water out.
Click and drag the scroll bar beneath the image below to solve the three associated questions.
Answers:
Text Version of the Challenge Question(s)
- a. If he blows the water vertically upward with a velocity of
how long will it take for the rock to reach its maximum height?
Answer:
- b. What will be the maximum height reached by the rock?
Answer:
- c. If the top of the elephant’s trunk in its upward position is
above the water level, find the speed of the rock when it reaches the surface of the water.
Answer:
Image Attributions
- Challenge Question Activity:
- “An elephant blowing water and a rock upwards” created by Juan Pablo Amorocho in the OER Lab at Centennial College