SIMPLE MACHINE

What is a simple machine?

• A. A machine with motors and electronics

• B. A tool that multiplies force or changes force direction

• C. A device that uses energy to create heat

• D. A complex system made up of multiple parts

Which formula correctly represents machine efficiency?

• A. Output Work ÷ Input Work × 100%

• B. Input Work ÷ Output Work × 100%

• C. (Output Work – Input Work) ÷ Input Work × 100%

• D. Output Energy ÷ Time × 100%

If a machine has 200 J of input work and 150 J of output work, what is its efficiency?

• A. 75%

• B. 150%

• C. 50%

• D. 100%

Which of the following is a compound machine?

• A. Pulley

• B. Lever

• C. Wheel & axle

• D. Bicycle

Which factor most directly reduces the useful output work of a machine?

• A. More mechanical advantage

• B. Reduced friction

• C. Excessive slipping

• D. Stronger materials

A machine with a high mechanical advantage (MA > 1) means:

• A. It always has 100% efficiency

• B. You need more input force than output force

• C. Output force is greater than input force, but efficiency may vary

• D. Its direction of force changes only

Why is an inclined plane often more efficient than trying to lift an object straight up?

• A. It reduces the weight of the object

• B. It spreads work over distance, requiring less force

• C. It has no friction

• D. It changes force direction only

Which of these demonstrates an efficient simple machine in practice?

• A. A pulley with a frayed rope

• B. A bicycle chain with stuck links

• C. A well‑lubricated bicycle gear system

• D. A rusty hinge on a gate

What is one effective way to reduce friction and improve machine efficiency?

• A. Paint moving parts

• B. Use heavier metals

• C. Apply lubricant oil

• D. Decrease mechanical advantage

Choosing ________, smoother materials and improving ________ design can increase the overall ________ of both simple and compound machines.