Simple Machines — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Which simple machine is a ramp an example of?
A) Lever
B) Wedge
C) Inclined plane
D) Pulley
A ramp is a flat surface that slopes upward, which is the very definition of an inclined plane. The other choices describe different machines: levers turn on a fulcrum, wedges split things, and pulleys use ropes and wheels.
2. How does a pulley make work easier?
A) It increases the weight of the load
B) It changes the direction of the force
C) It removes all friction
D) It makes objects lighter
When you pull down on the rope of a fixed pulley, the load on the other end rises, so the pulley flips the direction of your effort. It does not change the weight of the load or remove friction.
3. A screw is best described as which of the following?
A) A flat surface used to slide objects
B) A bar that turns on a fulcrum
C) An inclined plane wrapped around a rod
D) A thin blade that splits things apart
If you could unwind the spiral threads of a screw, they would stretch out into a long sloped surface, which is why a screw is described as an inclined plane wrapped around a rod.
4. Which pair of objects are both examples of a wedge?
A) Doorknob and steering wheel
B) Knife and axe
C) Seesaw and crowbar
D) Flagpole rope and blinds cord
Both a knife and an axe have a thick back and a thin cutting edge that pushes material apart, which is the shape of a wedge. The other pairs are wheels and axles or lever and pulley examples.
Part B: Fill in the Blank
Write the correct answer on each line.
1. A lever needs a fulcrum to work as a turning point.
A lever is a stiff bar that needs a fixed pivot so it can swing up and down. That pivot point is called the fulcrum.
2. A wheelbarrow combines a lever and a wheel and axle.
A wheelbarrow has long handles you lift like a lever, and the front wheel spins on a rod so the load can roll. The rod the wheel spins on is the axle.
3. Simple machines make work easier by reducing the force you must apply.
Simple machines let you spread the same job over a longer push or pull, so each moment feels easier. The thing they reduce is the force you have to apply.
4. A zipper uses tiny wedges that lock and unlock as you pull the tab.
A zipper closes by pushing two rows of teeth together using small thick-to-thin sliders inside the tab. Those tiny splitting tools are wedges.
5. Moving a piano up a long ramp requires less force but more distance.
A long ramp is gentler, so you only need a small push at any moment, but you have to keep pushing the piano along a much longer path. That extra path is the distance.