Question 1: What is the unit of measurement for work?

Answer: Joule

Question 2: True or False: Power is defined as the rate at which work is done.

Answer: True

Question 3: Define the term 'efficiency' in the context of energy transfer.

Answer: Efficiency is the ratio of useful energy output to total energy input, expressed as a percentage.

Question 4: Match the following terms to their definitions:

Answer: See full answer key

Question 5: Calculate the work done when a force of 10 N moves an object 5 meters.

Answer: 50 Joules

Question 6: Describe how the efficiency of a machine can be improved.

Answer: Efficiency can be improved by reducing energy waste, such as friction, and ensuring more energy is used for useful work.

Question 7: True or False: The formula for power is Power = Work / Time.

Answer: True

Question 8: Place the following steps in order to calculate efficiency: 1. Measure the total energy input. 2. Measure the useful energy output. 3. Divide the useful energy output by the total energy input and multiply by 100.

Answer: See full answer key

Question 9: Fill in the blank: The power of a machine is the ___ at which work is performed.

Answer: rate

Question 10: Explain why a machine can never be 100% efficient.

Answer: A machine can never be 100% efficient because some energy is always lost as waste heat due to friction and other resistive forces. This energy loss prevents all input energy from being converted into useful work.

Question 11: What happens to the efficiency of a machine if the friction in its components is reduced?

Answer: The efficiency of the machine increases because less energy is lost to overcome friction, resulting in more energy being used for useful work.

Question 12: Which of the following formulas is used to calculate work done? A) Work = Force x Distance B) Work = Force + Distance C) Work = Force - Distance D) Work = Force / Distance

Answer: Work = Force x Distance

Question 13: Calculate the power output if 100 Joules of work is done in 5 seconds.

Answer: 20 Watts

Question 14: What is the effect of increasing the time taken to do a certain amount of work on the power output?

Answer: Increasing the time taken decreases the power output because power is inversely proportional to time for a fixed amount of work.

Question 15: Identify two factors that can reduce the efficiency of a machine.

Answer: Friction and air resistance are two factors that can reduce the efficiency of a machine.