3.4.1.7 Work, Energy and Power Flashcards
When is work done?
Work is done whenever energy is transferred.
What is needed to move something?
A force is needed to move something because you need to overcome another force. The thing being moved has kinetic energy while its moving. The kinetic energy is transferred to another form of energy when the movement stops.
What is the equation for work?
Work done = force causing motion x distance moved in the direction of the force.
What is the definition of 1 Joule?
One joule is the work done when a force of 1 newton moves an object through a distance of 1 metre.
Which equation is used when the force and movement are not in the same direction?
Work done = force x distance x cosX,
where X is the angle between the direction of the force and the direction of motion.
What does the area under a force-displacement graph give?
Work done.
When is a force displacement graph used?
When the force is variable.
What is power?
Power is the rate of work done, or the rate of energy transfer.
What is the equation for power?
Power = change in work done / change in time.
What is the unit for power?
The unit for power is the watt, which is defined as a rate of energy transfer equal to 1 joule per second.
Give another equation for power.
Power = Force x Velocity.
