Simple Machines — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Which simple machine is found inside a pencil sharpener?
A) Lever
B) Pulley
C) Wedge
D) Inclined plane
The sharp blade inside a pencil sharpener is a wedge because it slices into the wood at an angle to shave it away from the graphite.
2. What advantage does a longer lever give you compared to a shorter one?
A) It weighs less
B) It needs less force to lift the same load
C) It removes all friction
D) It makes the load disappear
A longer lever gives you a bigger effort arm, so you can lift the same heavy load using less force than a shorter lever would require.
3. A doorstop keeps a door open. Which simple machine does it act as?
A) Screw
B) Pulley
C) Wedge
D) Wheel and axle
A doorstop is a wedge because its thin, angled shape slides under the door and pushes against the floor to hold the door in place.
4. Why do screws with more threads per inch hold tighter?
A) They are made of stronger metal
B) They have a longer inclined plane wrapped more tightly
C) They are always bigger
D) They use pulleys inside the wood
More threads per inch means a longer inclined plane is wrapped more tightly around the shaft, giving the screw more surface area to grip the material.
Part B: Fill in the Blank
Write the correct answer on each line.
1. A can opener combines a wedge, a lever, and a wheel and axle.
A can opener uses three simple machines together: a wedge to cut the metal, a lever to press down, and a wheel and axle to turn and move around the rim.
2. An escalator is a moving inclined plane that carries people up or down.
An escalator is an inclined plane with moving steps, so people ride the sloped surface up or down without having to climb on their own.
3. A longer ramp uses more distance but requires less force to reach the top.
A longer ramp means you travel more distance, but the trade-off is that you need less force with each step to reach the same height.
4. Blinds on a window go up and down by pulling a cord attached to a pulley.
Window blinds use a pulley so that when you pull the cord down, the blinds move up, changing the direction of the force you apply.
5. Mechanical advantage tells you how many times a machine multiplies your force.
Mechanical advantage is the number that shows how many times a machine multiplies the force you put in, helping you know how much easier the machine makes the job.