University of Virginia
Physics Department

Newton's First Law: Observing Inertia

A Physical Science Activity

Student Activity

Materials

• 2 ring stands
• Cardboard (20 cm x 5 cm)
• Small cart with wheels (can be ordered from Frey Scientific Catalog (1-888-222-1332); item number SO4480)
• 100 g mass
• Metric ruler or meter stick
• Sandpaper

Procedure

1. Place the two ring stands about 20 cm apart on the floor or on a large surface.
2. Tape the cardboard to the ring stands so that it spans the area between them. Make sure the cardboard is close enough to the floor so that the cart cannot fit underneath it.
3. Place the 100 g mass inside the cart. Set the cart on the floor at least 1 meter from the cardboard.

4. Place a piece of tape on the cart underneath the spot where the mass is initially set.
5. Gently push the cart towards the cardboard so that the cart strikes it. Measure the distance that the mass travels from its starting point on the cart and record it on the data table.
6. Replace the mass in its original position. Repeat step 5, but push the cart with a greater force.
7. Measure the distance that the mass travels from its starting point on the cart and record it.
8. Replace the mass in its original position and secure it with a piece of masking tape.
9. Push the cart with the same force as in step 6, and observe what happens to the mass. Record this.
10. Remove the mass from the cart. Tape a piece of sandpaper, cut to fit, onto the cart.
11. Replace the mass in its original position.
12. Gently push the cart into the cardboard and record the distance traveled by the mass.
13. Replace the mass, and push the cart with a greater force into the cardboard. Record the distance.
14. Tape the mass in its original position. Push the cart with the same force as in step 13, and record the observation.

Data Sheet

 Distance traveled by mass Observations First trial (no sandpaper) Gentle push Fast push Mass taped down Second trial (sandpaper) Gentle push Fast push Mass taped down

Questions

1. Describe the forces acting upon the cart when it comes in contact with the cardboard. How does this explain its change in motion?

2. Describe the forces acting upon the mass at the point of collision. How does this explain its motion?

3. Did the addition of sandpaper to the cart affect your results? Why or why not?