Name________________________________________ Date_______________ Period_______
Kibala CP Physics
Section 4 Free Fall and Horizontal Projectile Motion
Free Fall Bleachers Lab
Objective:
1) To solve for the acceleration due to gravity.
2) Use acceleration due to gravity to calculate the height of the bleachers.
Procedure (Part1): Use a string and a meter stick to measure the height of the
bleachers. Drop a tennis ball 3 times and time its trip to the ground each time. Find
an average time to the ground
Time of 3 drops:
1) ____________________
2) ____________________
3) ____________________
(height of bleachers) d = ________________
(average time to ground) t= _________________
(acceleration due to gravity) g= ?
Calculate the acceleration due to gravity below:
d = 1/2 gt2
Procedure (Part2): Use the “g” that you calculated to measure the height of the
bleachers. Drop the ball 3 times again and calculate an average time it takes the ball
to reach the ground.
Givens:
Time of 3 drops:
1) ____________________
2) ____________________
3) ____________________
(height of bleachers) d = ?
g = 9.8 m/s2
(average time it takes the ball to reach the ground) t= _________________
Calculate the height of the bleachers below:
d=1/2gt2
Procedure (Part3): Now drop a water ball 3 times off the bleachers and find an
average time it takes the water ball to reach the ground. Calculate the acceleration
due to gravity of the water ball below:
Time of 3 drops:
1) ____________________
2) ____________________
3) ____________________
(height of bleachers) d = ________________
(average time to ground) t= _________________
(acceleration due to gravity) g= ?
Calculate the acceleration due to gravity below:
d=1/2gt2
Analysis Questions:
1) When did you calculate a greater acceleration due to gravity: When you
dropped the tennis ball or the water ball?
2) Explain why you calculated a greater acceleration for one object and a
smaller acceleration for the other object? Which object did the air affect
more?
3) What would happen if you dropped both the tennis ball and water ball at the
same time from the bleachers? Which would hit first? Why?
4) What would happen if you dropped both the tennis ball and water ball at the
same time from the bleachers in a vacuum? Explain.
5) The water ball has the same mass as a piece of paper. Why does a piece of
paper take more time to hit the ground than the water ball?
6) At the end of the water balls run you may have noticed that it seemed to stop
speeding up and hit a top speed in the couple feet before it hit the ground.
The water ball continued at that constant speed until it hit the ground.
a. Draw a strobe photo for the water ball
b. Draw a sketch of a distance versus time graph of the water ball.
c. Draw a force diagram and sum the forces in the y direction for the
water ball right after it was first dropped.
d. Draw a force diagram and sum the forces in the y direction for the
water ball in the interval it traveled at constant speed just before it hit
the ground.