Simple Machines — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A ramp is an example of an inclined plane.
A ramp is a flat surface tilted higher on one end so things can slide or be pushed up gradually. The full name for that tilted flat surface is an inclined plane.
2. A pulley changes the direction of a force using a rope and a grooved wheel.
A grooved wheel with a rope running over it lets you pull down on one end to lift a load on the other end, flipping the direction of your effort. That tool is a pulley.
3. The fixed point on which a lever turns is called the fulcrum.
Every lever needs a stationary point to turn against so the bar can rock up and down, and that fixed turning point is the fulcrum.
4. A screw is really an inclined plane wrapped in a spiral shape.
If you imagine unwinding the threads of a screw, they form a long inclined plane that has been twisted around a rod. That twisted shape is a spiral.
5. A knife blade is an example of a wedge because it splits things apart.
A knife blade is thick at the top and tapers to a thin sharp edge that pushes food apart as it cuts. That splitting shape is a wedge.
6. A steering wheel is an example of a wheel and axle.
A steering wheel is the round part the driver grips, and it turns a thin rod that steers the car. The rod the wheel spins is the axle.
7. Simple machines reduce the amount of force needed to do work.
Simple machines let you trade muscle work for distance, so you push less hard but for longer. The thing they reduce is the force needed.
8. A wheelchair ramp makes it easier to move up by increasing the distance.
A wheelchair ramp replaces a short, steep lift with a long, gentle slope, so the climber pushes less hard but travels farther. The missing word is distance.
9. A bottle cap is removed by turning, which uses a screw simple machine.
A bottle cap has spiral grooves that match the spiral grooves on the bottle neck, and twisting it loose works the same way the threads on a screw do.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Lever
→ Bar that turns on a fulcrum
Rope and wheel to lift loads
Inclined plane
→ Flat sloping surface
Bar that turns on a fulcrum
Wedge
→ Thin edge that splits things
Flat sloping surface
Pulley
→ Rope and wheel to lift loads
Thin edge that splits things
Each simple machine is matched to its description. A lever is a bar that turns on a fulcrum, an inclined plane is a flat sloping surface, a wedge is a thin edge that splits things, and a pulley uses a rope and wheel to lift loads.