Simple Machines
Levers, pulleys and ramps trade force for distance.
About this topic
Simple machines such as levers, pulleys, inclined planes, wedges, wheels and axles, and screws make work easier by changing the size or direction of a force. They can't reduce the work needed: a smaller force acts over a larger distance.
Mechanical advantage is output force divided by input force. A long crowbar has a large advantage because the effort arm is longer than the load arm. A ramp's ideal advantage is its length divided by its height, and a pulley system's is about the number of supporting rope sections. In practice friction means the actual advantage is smaller and efficiency is below 100%.
Example: using a 2 m ramp to raise a 100 kg box by 0.5 m needs about 245 N instead of 980 N, but you push four times as far. A pair of scissors, a bottle opener, a wheelbarrow, a screw jack and a bicycle gear all show the same trade-off.
Misconception: machines do not give you free energy. They trade force for distance, so the work in equals the work out for an ideal machine. Always compare both the force and the distance moved.
Key ideas
- Mechanical advantage = load ÷ effort
- Work in equals work out (ideal)
- Longer ramps need less force
Quick check
Use cases: where Simple Machines helps
- Homework: review the key idea behind Simple Machines before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Simple Machines without notes.
- Visual learning: play with the interactive lab to see how Simple Machines changes when you adjust its inputs.
- Teaching a friend: explain Simple Machines in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Simple Machines?
Levers, pulleys and ramps trade force for distance.
What will I learn in Simple Machines?
Mechanical advantage = load ÷ effort. Work in equals work out (ideal). Longer ramps need less force.
Is Simple Machines part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Simple Machines lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Simple Machines?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.