Force & Motion — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Maya rolled a toy car down a ramp onto four surfaces. Carpet: 20 cm. Grass mat: 30 cm. Wood floor: 90 cm. Tile: 110 cm. Which surface let the car go the farthest?
A) Carpet
B) Grass mat
C) Wood floor
D) Tile
Tile had the smoothest surface and the least friction, so the car rolled 110 cm, the longest distance.
2. In the same test, which surface slowed the car the most?
A) Tile
B) Wood floor
C) Grass mat
D) Carpet
Carpet has lots of fibers that create friction, so the car only rolled 20 cm before stopping.
3. Leo tested a toy car down the same ramp three times on a tile floor and got 108, 110, and 112 cm. What is the BEST conclusion?
A) The results are almost the same, showing the test is fair
B) Tile makes cars slower than carpet
C) The ramp was broken
D) Friction made the car stop right away
Close results across trials show the experiment is reliable and the distances on tile are consistent.
4. Which change would MOST LIKELY make the toy car roll even farther on tile?
A) Putting sand on the tile
B) Raising the ramp higher
C) Adding a rug on the tile
D) Pushing less from the top
A higher ramp gives the car more starting speed from gravity, so it rolls even farther across the tile.
Part B: Fill in the Blank
Write the correct answer on each line.
1. A smooth surface like tile has less friction than a rough surface like carpet.
Smooth surfaces have fewer bumps to grab the wheels, so friction is lower on tile.
2. When friction is lower, a rolling car travels a greater distance.
Less friction means less of the car's energy is lost, so it can roll farther.
3. Running an experiment three times and getting close numbers makes the results more reliable.
Repeating a test and getting similar numbers shows the results are consistent and trustworthy.
4. To test surfaces fairly, everything else in the experiment must be kept the same.
A fair test keeps all variables constant except the one you are testing, like the surface.
5. Raising the ramp higher gives the car more starting speed.
A taller ramp means the car gains more speed from gravity before reaching the bottom.