Critical Thinking Items
9.1 Work, Power, and the Work–Energy Theorem
Which activity requires a person to exert force on an object that causes the object to move but does not change the kinetic or potential energy of the object?
- Moving an object to a greater height with acceleration
- Moving an object to a greater height without acceleration
- Carrying an object with acceleration at the same height
- Carrying an object without acceleration at the same height
Which statement explains how it is possible to carry books to school without changing the kinetic or potential energy of the books or doing any work?
- By moving the book without acceleration and keeping the height of the book constant
- By moving the book with acceleration and keeping the height of the book constant
- By moving the book without acceleration and changing the height of the book
- By moving the book with acceleration and changing the height of the book
9.2 Mechanical Energy and Conservation of Energy
True or false—A cyclist coasts down one hill and up another hill until she comes to a stop. The point at which the bicycle stops is lower than the point at which it started coasting because part of the original potential energy has been converted to a quantity of heat and this makes the tires of the bicycle warm.
- True
- False