Work and Energy

Topics in this chapter

• Work, Force, and Displacement
• Work Sign and Angle
• Kinetic Energy and Work
• Potential and Mechanical Energy
• Energy Conservation and Transformation
• Power and Commercial Energy Units

Cheat sheet

Practice questions

1. Question 1Q-2AF0AD

   When is the work done by a force on an object said to be negative?

   1. A.The force and displacement are in the same direction.
   2. B.The force and displacement are in opposite directions.
   3. C.The force is perpendicular to the displacement.
   4. D.The displacement of the object is zero.
   See the answer and solution
2. Question 2Q-634B72

   Which of the following units is equivalent to a Joule (J)?

   1. A.kg m s^-1
   2. B.kg m^2 s^-2
   3. C.kg m s^-2
   4. D.kg^2 m s^-2
   See the answer and solution
3. Question 3Q-63BC8A

   A girl is carrying a school bag of mass 3 kg on her back and walks a horizontal distance of 100 m. How much work is done by the girl against the force of gravity? (Take $g = 9.8\text{ m/s}^2$)

   1. A.2940 J
   2. B.300 J
   3. C.0 J
   4. D.294 J
   See the answer and solution
4. Question 4Q-1A53BB

   If the power of an electric bulb is 40 W, how much electrical energy does it consume in 2 minutes?

   1. A.80 J
   2. B.2400 J
   3. C.4800 J
   4. D.8000 J
   See the answer and solution
5. Question 5Q-7E676A

   According to the Law of Conservation of Energy, energy can be:

   1. A.Created and destroyed
   2. B.Created only
   3. C.Converted from one form to another, but total energy remains constant
   4. D.Destroyed only to create work
   See the answer and solution