Power and the Rate of Doing Work

Try these questions

5 questions from this lesson’s quiz. Start the lesson to answer them and see the right answers.

1. 1. Which statement gives the correct scientific definition of power?

   • A. The force needed to move an object over a distance
   • B. The rate at which work is done or energy is transferred
   • C. The total energy stored in an object
   • D. The distance an object moves in one second

2. 2. A student weighing 500 N climbs a flight of stairs of vertical height 3.0 m in 5.0 s. Calculate the student's power output.

   Type your answer (in W) in the lesson.

3. 3. Two hikers of equal mass climb the same trail to the top of Mount Longonot. Hiker A takes 2 hours and Hiker B takes 40 minutes. Which quantity is different for the two hikers?

   • A. The work done against gravity
   • B. The weight of each hiker
   • C. The power output
   • D. The height climbed

4. 4. An electric kettle has a power rating of 2 kW. How much energy does it transfer when it runs for 3 minutes?

   Type your answer (in J) in the lesson.

5. 5. A 2,000 W kettle runs for 3 minutes. A 100 W television is left on for 5 hours. Which statement is correct?

   • A. The kettle uses more energy because its power is higher
   • B. Both use the same amount of energy
   • C. The television uses more energy because it runs for much longer
   • D. The kettle uses 5 times more energy than the television

More in Energy, Work, Power and Machines

• ▸Torque, Couples and Resolution of Forces
• ▸Practical Applications and System Consolidation
• ▸Forms of Energy & Conservation
• ▸Concept and Measurement of Work
• ▸Introduction to Machines, Mechanical Advantage and Velocity Ratio
• ▸Machine Efficiency and Energy Losses
• ▸Levers and the Principle of Moments
• ▸Pulleys and Pulley Belt Systems

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