Simple Machines — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A hammer claw pulls nails out of wood by working as a lever.
The claw end of a hammer is a lever because you push down on the handle and the claw pivots against the hammer head to pull the nail upward out of the wood.
2. The threads on a bolt are shaped like an inclined plane wrapped in a spiral.
Bolt threads wind around the shaft in a spiral, which is an inclined plane wrapped around a cylinder so it can grip and hold tightly.
3. A pizza cutter uses a wheel and axle to roll across the dough.
The round blade of a pizza cutter is the wheel, and the pin it spins on is the axle, letting the blade roll and slice through the dough.
4. A chisel is a wedge that carves and splits stone or wood.
A chisel has a thin, angled edge that pushes material apart when struck, which is exactly how a wedge works to split stone or wood.
5. A crane at a construction site uses a pulley to lift steel beams.
A crane uses a pulley system with ropes and wheels so workers can pull a cable one direction and the heavy steel beam moves upward.
6. Loading a truck by pushing boxes up a ramp uses an inclined plane.
A ramp is an inclined plane because its sloped surface lets you push a heavy box upward with less force than lifting it straight up.
7. When you move the fulcrum closer to the load, the lever needs less force.
Moving the fulcrum closer to the load gives you a longer effort arm, so you need less force to lift the same heavy object.
8. A wood screw is a type of screw that holds two boards together.
A wood screw has spiral threads that dig into the wood as you turn it, gripping the boards tightly and holding them together.
9. Simple machines change the direction or amount of force needed to do work.
Simple machines make work easier by changing how much force you need or which direction you push or pull, even though the total work stays the same.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Scissors
→ Two levers joined together
Wheel and axle
Slide
→ Inclined plane
Pulley
Doorknob
→ Wheel and axle
Inclined plane
Flagpole rope
→ Pulley
Two levers joined together
Correct matches: Scissors → Two levers joined together; Slide → Inclined plane; Doorknob → Wheel and axle; Flagpole rope → Pulley.