Question
Which are true about the energy of a swinging weight—a pendulum—as it swings?
Multiple select question.
Its kinetic energy is zero at the bottom of the swing.
Its potential energy is at a maximum at the top of the swing.
It has potential energy when it is above its resting point.
Its potential energy remains constant throughout the swing.
It has kinetic energy when it is moving.
Its kinetic energy is zero at the moment it changes direction.
Multiple select question.
Its kinetic energy is zero at the bottom of the swing.
Its potential energy is at a maximum at the top of the swing.
It has potential energy when it is above its resting point.
Its potential energy remains constant throughout the swing.
It has kinetic energy when it is moving.
Its kinetic energy is zero at the moment it changes direction.
Answers
GPT-4o mini
Let's analyze each statement regarding the energy of a swinging weight (pendulum):
1. **Its kinetic energy is zero at the bottom of the swing.**
**False.** At the bottom of the swing, the pendulum has maximum kinetic energy since this is where it is moving fastest.
2. **Its potential energy is at a maximum at the top of the swing.**
**True.** At the highest points of the swing, the pendulum's potential energy is maximized due to its elevated position.
3. **It has potential energy when it is above its resting point.**
**True.** When the pendulum is above its lowest resting point, it possesses gravitational potential energy.
4. **Its potential energy remains constant throughout the swing.**
**False.** The potential energy changes as the pendulum moves up and down; it is highest at the top and lowest at the bottom.
5. **It has kinetic energy when it is moving.**
**True.** When the pendulum is in motion, it possesses kinetic energy.
6. **Its kinetic energy is zero at the moment it changes direction.**
**True.** At the moment the pendulum changes direction (i.e., at the top of its swing), its velocity is zero, meaning its kinetic energy is also zero.
In summary, the true statements are:
- Its potential energy is at a maximum at the top of the swing.
- It has potential energy when it is above its resting point.
- It has kinetic energy when it is moving.
- Its kinetic energy is zero at the moment it changes direction.
1. **Its kinetic energy is zero at the bottom of the swing.**
**False.** At the bottom of the swing, the pendulum has maximum kinetic energy since this is where it is moving fastest.
2. **Its potential energy is at a maximum at the top of the swing.**
**True.** At the highest points of the swing, the pendulum's potential energy is maximized due to its elevated position.
3. **It has potential energy when it is above its resting point.**
**True.** When the pendulum is above its lowest resting point, it possesses gravitational potential energy.
4. **Its potential energy remains constant throughout the swing.**
**False.** The potential energy changes as the pendulum moves up and down; it is highest at the top and lowest at the bottom.
5. **It has kinetic energy when it is moving.**
**True.** When the pendulum is in motion, it possesses kinetic energy.
6. **Its kinetic energy is zero at the moment it changes direction.**
**True.** At the moment the pendulum changes direction (i.e., at the top of its swing), its velocity is zero, meaning its kinetic energy is also zero.
In summary, the true statements are:
- Its potential energy is at a maximum at the top of the swing.
- It has potential energy when it is above its resting point.
- It has kinetic energy when it is moving.
- Its kinetic energy is zero at the moment it changes direction.