Discovery Lab
PUSHES AND PULLS
2nd Grade
Station #1: Force and Motion
Supplies:
PVC pipe approximately 53 cm long (this item is labeled and is located in the Discovery
Lab closet)
Small glass ball
Small wooden ball
Small metal ball
Small Scale
*Additional balls can be ordered from Arbor Scientific (www.arborsci.com)
Plastic hamster house with an opening
Masking tape
Measuring stick or tape
6 – 2 lb. bricks (can be found in Discovery Lab closet)
18 hexagonal shaped one pound weights (located in the DL bin marked weights)
Note: the wood, glass and metal balls should all be approximately the same diameter.
Concepts to be learned


Understand how motion or distance traveled depends on mass and force.
Investigate the relationship between force, mass, and acceleration as described by
Newton’s 2nd Law of Motion.
Background Information
This experiment is designed to verify Newton’s 2nd Law of Motion. This law states that a
force on an object will cause it to accelerate in the direction of the force. The greater the
force exerted on the object, the greater the acceleration. For any given force, the greater
the mass of an object, the smaller the acceleration.
In this experiment, the force will be applied by rolling balls of different masses down a
ramp (PVC pipe). A wooden, glass, and metal ball will be used to vary the force used. A
hamster house will be used to measure the acceleration by measuring how far it travels
after being hit by the ball. The plastic hamster house will be placed at the bottom of the
ramp to catch the balls. The greater the mass of the ball rolling down the ramp, the
farther the box should travel.
Part 1
*DO NOT LET THE CHILDREN LIFT THE WEIGHTS AND
BRICKS OR PUT THEIR HANDS NEAR THE HAMSTER HOUSE
WHEN IT HAS THE WEIGHTS ON TOP!
1. Prior to the beginning of the lab, mark a starting point on the floor with masking
tape. Be sure to place the tape where the path of the ball will not be interrupted
by the metal connectors on the floor of the lab.
2. Create a ramp using the PVC pipe. Place one end of the ramp on the masking
tape.
3. Place the hamster house in front of the ramp, with the opening facing the ramp,
so it will catch a ball as it is rolled down the ramp. (The end with the hamster
house will be the bottom of the ramp.)
4. Rest the other end of the pipe (ramp) on the seat of a chair. (Hold the pipe in
place so it doesn’t fall off the chair.) Continue to keep the pipe at the same
incline for all experiments at this station
5. Ask a student to weigh the wooden ball on the scale. Instruct the students to
record the weight on their worksheets. Roll the wooden ball down the ramp and
measure how far the hamster house moved from its starting position. Have the
students record this on their worksheets.
6. Repeat the experiment using a glass ball. Ask a student to weigh the glass ball
on the scale. Instruct the students to record the weight on their worksheets.
Point out to the students that it weighs more than the wooden ball. Ask the
students to predict if the hamster cage will move the same distance or a greater
distance since the glass ball has a greater mass than the wooden ball. Roll the
glass ball down the ramp with one end resting on the seat of the chair. Make
sure the hamster house is properly positioned in front of the ramp and that the
end of the pipe is on the masking tape. Measure how far the hamster house
moved from its starting position. Have the students record this on their
worksheets.
7. Repeat the experiment using a metal ball. Ask a student to weigh the metal ball.
Instruct the students to record the weight on their worksheets. Point out that the
metal ball weighs more than both the wooden ball and the glass balls. Ask the
students to predict if the heavier ball will push the hamster house further than
the wooden and glass balls. Make sure the hamster house is properly positioned
in front of the ramp and that the end of the pipe is on the masking tape.
8. Roll the metal ball down the ramp and measure how far the hamster house
moved from its starting position. Have the students record this on their
worksheets.
9. Point out to the students that because it has a greater mass, it pushed the hamster
house further than the other two balls.
10. Discuss with the students what occurred. By increasing the mass of the moving
object, we increased the distance moved by the hamster house. The wooden
ball had the least mass and moved the hamster house the shortest distance. The
metal ball had the greatest mass and moved the hamster house the greatest
distance. The glass ball, had a mass greater than the wooden ball and and less
than the metal ball so the distance moved by the hamster house was between the
other two balls.
Part 2
Now we are going to change the mass of the object at rest and conduct an experiment
to determine how this affects the distance travelled by the hamster house when hit by the
force of the metal ball.
1. Again, place one end of the ramp (PVC pipe) on the masking tape.
2. Place the hamster house in front of the ramp with the opening facing the ramp,
so it will catch a ball as it is rolled down the ramp. (The end with the hamster
house will be the bottom of the ramp.)
3. Hold the other end of the pipe (ramp) on the seat of a chair. (Hold the pipe in
place so it doesn’t fall off the chair.) Continue to keep the pipe at the same
incline for the duration of all experiments at this station. If the ramp is not
kept at the same incline, the results will vary and you will run out of
weights before the hamster house stops moving.
4. Show the students a 1 pound weight. Ask the students if they think that adding
the weight to the top of the hamster house will keep it from moving when the
metal ball is rolled down the ramp?
5. Place the weight on top of the hamster house.
6. Roll the metal ball down the same ramp and measure how far the hamster house
moved.
7. Compare this to the results recorded in step 8 of part 1 above. Point out to the
students that the house did not move as far as it did when there was no weight
on the house. This is because the mass of the item at rest (the hamster house)
had increased and it would now require a greater force to move the house the
same distance.
8. Remove the weight from the top of the hamster house and retrieve the ball from
inside the house. Show the students a brick. Tell the students that the brick
weighs 2 pounds. Ask the students if they think that adding a brick to the top of
the hamster house will keep it from moving when the metal ball is rolled down
the ramp?
9. Set the brick on top of the hamster house.
10. Roll the metal ball down the same ramp and measure how far the hamster house
moved. Again, point out that the house did not move as far due to the additional
weight on the hamster house
11. Remove the brick and retrieve the ball from inside the hamster house. Now put
two bricks on the top of the hamster house. Ask the students to predict what will
happen to the hamster house. Will it move a shorter distance or a longer
distance than in step 4 above? Will it move at all?
12. Roll the metal ball down the same ramp and observe how far the hamster house
moved from its starting position.
13. Continue repeating the experiment, adding 2 bricks at a time until you use all 6
bricks. Then begin adding 4 metal weights (4 lbs.) at a time until the hamster
house no longer moves. Remember to retrieve the metal ball from under the
house each time. Remind the students to be careful not to drop the weights and
bricks on their fingers.
14. When the hamster house finally does not move when the metal ball is rolled
down the ramp, point out to the students that the house did not move because
the mass of the item at rest (the hamster house) was now greater than the force
(push) of the moving object (the metal ball).
15. Ask the students to add up the weight of all the bricks and metal weights they
used to determine how much weight was required to keep the hamster house
from moving, (When we tested the experiment, it took 6 – 2 lb. bricks and 16 –
1 lb. weights – 28 lbs. total to completely stop the house from moving.) Ask the
students to record the actual weight on their worksheets.
16. Remind the students of the following concepts:
 The more force (greater mass of the ball), the farther the house will travel.
 The more mass (number of weights), the shorter the distance the house
will travel.
 The greater the force of the moving object (mass), the greater the distance
the object at rest will move. The greater the mass of the object at rest,
the less it will move.