Unit 3 - Lesson 12: Work and Power Flashcards
Force causes movement (acceleration) due to what equation?
F = ma and/or F = mv - mu/t
The more the object moves, the more work is done. True or false?
True.
What is the equation to find the work?
Work = Force x distance
W = F x d
If you plug in distance as metres and force as Newtons, work will be calculated in what unit?
Joules
The greater the force, the (more/less) work requires to move it a set distance.
The greater the force, the MORE work required to move it a set distance.
The greater the distance moved, the (more/less) work is needed.
The greater the distance, the MORE work is needed.
For example, a man is pushing a force of 20 Newtons for a distance of 3 metres. How much work has he done?
W = 20 x 3
W = 60 j
If there is no movement, there is no work done. True or false?
True.
When energy is transferred from one form to another, what has been done?
Work.
A weightlifter transfers energy from his chemical store (food) to the weights, increasing their gravitational potential energy. As energy is transferred, what is done?
Work. I.E. The force (weight) is moved up by some distance.
A ball has more gravitational potential energy at the top of a ledge. When the woman drops the ball, the gravitational potential energy is transferred to kinetic (movement) energy. What is done in the process?
Work. I.E. The ball with the force of weight moves.
What does work equire?
Energy.
What is ‘Work Done’ equal to? Why?
Work Done = Energy Transferred
Work done is equal to energy transferred because even if energy is wasted, if there is an energy transfer, work is done.
What unit is work done measured in? Therefore, what unit is energy also measured in?
Joules.
When a force moves an object through a distance, what is done in the process?
Work is done on the object AND energy is transferred.
To calculate energy transferred or work in joules, you must enter distance in what unit and force in what unit?
You must enter distance in metres and force in Newtons to the formula (W = F x d). If you’re not given these units for force & distance, please convert them into metres and Newtons.
How do you convert kJ into j?
Multiply kJ by 1000
How do you convert j into kJ?
Divide j by 1000.
How do you convert MJ into j?
Multiply MJ by 1,000,000.
How do you convert j into MJ?
Divide j by 1,000,000.
How do you convert kJ into MJ?
Divide kJ by 1000.
How do you convert MJ into kJ?
Multiply MJ by 1000.
What is power?
Power is the rate at which work is done.
What is power measured in?
j/s (number of joules of energy transferred per second)
