Energy of motion
Kinetic energy.
A parked and a moving cycle
A cycle stands parked. Then someone rides it down the road. A moving cycle can knock over a bucket in its way, a parked one does not.
What do you think is different about the moving cycle?
What this lesson covers
The idea
The energy an object possesses due to its motion is its kinetic energy; all moving objects have it, and an object that does not move is taken to have zero kinetic energy.
A parked and a moving cycle
A cycle stands parked. Then someone rides it down the road. A moving cycle can knock over a bucket in its way, a parked one does not.
What do you think is different about the moving cycle?
- It has energy because of its motion
- It has less energy
- It has no energy
Which have it?
Sort each object: does it have kinetic energy, or zero?
Motion means kinetic energy
Everything in the left group is moving. An object that does not move is taken to have zero kinetic energy.
The energy an object possesses due to its motion is its kinetic energy. All moving objects have it, such as a moving bicycle or a rolling ball. An object that does not move is taken to have zero kinetic energy.
Notes
Kinetic energy is the energy due to motion. Moving objects have it; an object that does not move has zero.
Check yourself
Kinetic energy is the energy an object has due to its…
A ball lies still on the ground. Its kinetic energy is…
Which of these has kinetic energy?
- height above the ground. Energy due to position, such as height, is potential energy.
- motion — correct. Yes!
- shape only. Energy due to a change of shape is potential energy. Kinetic energy is due to motion.
- large, since it is heavy. Kinetic energy depends on motion. An object that does not move is taken to have zero kinetic energy.
- equal to its potential energy. The two are different kinds of energy. A ball that is not moving has zero kinetic energy.
- zero — correct. Yes!
- A rolling ball — correct. Yes!
- A parked bicycle. It does not move, so it is taken to have zero kinetic energy.
- A book resting on a table. It does not move, so it is taken to have zero kinetic energy.