Simple Machines — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A seesaw at the playground is an example of a lever.
A seesaw is a stiff plank that balances and turns on a bar in the middle, which is the classic lever setup with a load on each end and a fulcrum between them.
2. A pulley helps you raise a flag to the top of a pole.
Pulling down on a rope that runs over a small wheel at the top of a flagpole sends the flag upward, and that rope-and-wheel arrangement is a pulley.
3. An axe blade pushes wood apart because it is a wedge.
An axe blade is thick at the back and thin at the cutting edge, so it pushes the wood sideways as it is driven down. That splitting shape is a wedge.
4. A jar lid works like a screw because it has spiral grooves.
A jar lid screws on with spiral grooves that wind around the jar, and a spiral thread on a rod is exactly what a screw is.
5. A doorknob turns around an axle to open the door.
A doorknob is the wheel part you grip, and it spins a thin rod that pulls the latch back. That rod the knob turns around is the axle.
6. Sliding a heavy box up a ramp uses an inclined plane.
A ramp is a flat slope that lets you push a box up gradually instead of lifting it straight up. The full name for that flat slope is an inclined plane.
7. A crowbar helps pry open a lid by acting as a lever.
A crowbar is a long stiff bar you slide under a lid and push down on one end so the other end pries the lid up. That makes it a lever.
8. Simple machines do not reduce the total work, but they reduce the force needed.
Simple machines trade distance for muscle work: you push a smaller amount but over a longer path, so the missing word is force.
9. A nail is a type of wedge that holds pieces of wood together.
A nail is thick at the head and tapers to a thin sharp point that pushes wood fibers apart as it is hammered in. That thick-to-thin shape makes it a wedge.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Wheel and axle
→ Doorknob that turns to open
Ramp to a building entrance
Screw
→ Spiral inclined plane on a rod
Spiral inclined plane on a rod
Inclined plane
→ Ramp to a building entrance
Seesaw on a playground
Lever
→ Seesaw on a playground
Doorknob that turns to open
Each item is matched to its real-world example. A doorknob turning to open is a wheel and axle, a spiral inclined plane on a rod is a screw, a ramp to a building entrance is an inclined plane, and a seesaw on a playground is a lever.