Chapter 10, Problem 1PQ

To determine

The questions that cannot be answered using conservation of energy principle.

Answer to Problem 1PQ

The questions that cannot be answered using conservation of energy principle are (b) and (c).

Explanation of Solution

Principle of conservation of energy as the name implies helps to calculate the energy by application energy conservation law. Energy is scalar quantity. It cannot be used to identify the direction.

Conclusion:

The direction measurement is not under the application of the principle of conservation of energy. The options (b) and (c) ask about the direction and velocity which cannot be used in the law of conservation of energy. Therefore, the questions that cannot be answered using conservation of energy principle are (b) and (c).

Using the principle of conservation of energy, the maximum height of the ball when tossed up at a given speed can be calculated. The initial kinetic energy of the tossed ball will be completely converted into potential energy at its maximum height. Using the principle of conservation of energy equation $E_K=E_P$ , Kinetic energy is equal to Potential energy at maximum height and $1/2m{v}^2=mgh$ where $m$ ,$v$ ,$g$ , and $h$  are the mass of the ball, initial speed of the ball, gravitational acceleration, and maximum height of the ball, the maximum height of the ball can be calculated. Therefore question (a) can be answered.