Pre assessment (Simple/Compound machine, Power, Efficiency)

Which of the following is a simple machine?

• Lever

• Bicycle

• Motor

• Engine

In a first-class lever, the fulcrum is located

• At one end of the lever

• In the middle of the lever

• At the load

• Directly under the input force

Which of the following examples best illustrates a compound machine?

• Scissors

• Screwdriver

• Pulley

• Wheelbarrow

In the formula for work, W=F×d, what does d represent?

• Depth

• Direction

• Displacement

• Distance

Which of the following statements is true about efficiency?

• It can be greater than 100%.

• It measures the output force.

• It is a ratio comparing input and output energy.

• It is measured in joules.

Which of these is an example of work being done?

• A person holding a box steady

• A car parked on a hill

• A book sliding across a table

• A tree standing upright

What unit is used to measure power in the International System of Units (SI)?

• Joules

• Watts

• Newtons

• Meters

A pulley system is used to lift a heavy box. If 50 J of work is done to lift it, but 10 J of energy is lost to friction, what is the efficiency of the pulley system?

• 50%

• 80%

• 100%

• 20%

A wedge is a simple machine that converts rotational motion into linear motion.

• True

• False

Power is defined as the rate at which work is done.

• True

• False