Forces and Motion — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A force that slows motion between two surfaces is called friction.
In Grade 3, friction is the force between two surfaces that rub, and it works against motion.
2. A rough surface like sandpaper has more friction than glass.
In Grade 3 science, rough surfaces like sandpaper create more friction than smooth surfaces like glass.
3. Ice feels slippery because it has very little friction.
In Grade 3, a thin layer on ice makes friction very low, which is why shoes slide easily.
4. Tire treads are the grooves that help a car grip the road.
In Grade 3 science, tire treads add rough edges that increase friction so tires grip and do not slide.
5. A box slides easily on a smooth floor because there is less friction.
In Grade 3, smooth floors cause less friction, so a box slides farther with the same push.
6. Rubbing your hands together fast makes them feel warm.
In Grade 3 science, friction between surfaces produces heat, which you feel as warmth in your hands.
7. A rubber shoe sole gives more grip than a plastic one.
In Grade 3, rubber has more friction with the ground, so it gives shoes a better grip than smooth plastic.
8. To slide faster on a slide, we choose a very smooth surface.
In Grade 3 science, a smoother slide has less friction, so kids slide down more quickly.
9. On icy roads, cars need chains to increase friction so they do not slip.
In Grade 3, chains add rough points that increase friction on ice, so cars can stop and steer safely.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Sandpaper on wood
→ A lot of friction, hard to slide
A lot of friction, hard to slide
A smooth ice rink
→ Very little friction, slides easily
Very little friction, slides easily
Rubber tires on a dry road
→ Enough friction to grip safely
Enough friction to grip safely
A greased metal slide
→ Low friction from a slippery coating
Low friction from a slippery coating
In Grade 3, rough sandpaper has high friction, ice has very little, rubber tires grip, and grease lowers friction on metal.