Physics Simple Machines and Efficiency

Which of the following is NOT a type of simple machine?

• LEVER

• PULLEY

• ENGINE

• WHEEL AND AXLE

What simple machine is used in scissors?

• INCLINED PLANE

• LEVER

• SCREW

• PULLEY

Which simple machine is designed to split objects apart?

• WEDGE

• PULLEY

• INCLINED PLANE

• SCREW

Which simple machine helps lift objects with a rope?

• PULLEY

• WEDGE

• INCLINED PLANE

• SCREW

What is the formula to calculate efficiency?

• Work Output ÷ Work Input × 100

• Work Input ÷ Work Output × 100

• Work Output + Work Input × 100

• Work Input × Work Output × 100

If a pulley has a work input of 50 J and a work output of 40 J, what is its efficiency?

• 20%

• 50%

• 80%

• 90%

Why are no machines 100% efficient?

• Machines always lose some energy to friction or heat.

• Machines don’t work perfectly.

• Machines use too much energy.

• Machines stop working after a while.

What is the main purpose of a simple machine?

• To increase effort

• To make work easier

• To use more energy

• To reduce friction

What type of simple machine is a ramp?

• LEVER

• WEDGE

• SCREW

• INCLINED PLANE

If a machine has 90% efficiency, what happens to the other 10% of the energy?

• It is stored in the machine.

• It is lost as heat or friction.

• It is converted into useful work.

• It disappears completely.