Work, Energy, Power Flashcards
Define work
Forces causes an object to move through a distance, or change its position
SI unit for work
Joule (J)
Formula for work
W = F X x
What does W stand for in work?
Work done in j
What does F stand for in work?
Force applied in N
What does x stand for in work?
Distance travelled in m
How many joules cover one metre?
1 joule of work is the amount of work done to cover a distance of 1m in the direction of force when a force if 1N is applied to body
List three requirements for work to be done?
- Applied force
- Object/body should move as a result of force
- Object move in direction of force
What is force done against?
Two forces - gravity + friction
What does it mean when push against something and it does not move?
No work done - no motion
What does it mean when you push something and moves by itself?
No work done over distance - no applied force
What does it mean when you walk with something in your hand?
no work done - applied force and motion were not in same direction
What must you calculate if work done in vertical plane?
Calculate weight before calculate work done
vertical
horizontal
Define energy
Ability to do work
SI unit for energy
Joule (J)
How many forms of energy are there?
- Chemical
- Potential
- Kinetic
- Energy waves
- Heat
- Sound
- Magnetism
- Electrical
- Nuclear
Potential energy
Ep = m.g.h
Kinetic energy
Ek = 1/2m .v2
Electrical energy
E = I . V . T
Define gravitational potential energy
Object is defined as the energy an object has because of its position in the field relative to some reference point
Gravitational potential energy
Ep = mgh
Ep stands for what in gravitational potential energy?
Gravitational potential energy - J
m stands for what in gravitational potential energy?
mass of object (kg)
g stands for what in gravitational potential energy?
acceleration due to gravity
h stands for what in gravitational potential energy?
vertical height of the object from ground level
Define kinetic energy
Of an object is the energy an object possesses as a result of its motion
Kinetic energy
Ek = 1/2mv2
Ek stands for what in kinetic energy?
Kinetic energy (J)
m stands for what in kinetic energy?
mass of object (kg)
v stands for what in kinetic energy?
Velocity/speed
Define mechanical energy
Sum of the gravitational potential and kinetic energy at a point
Mechanical energy
EM = Ep + Ek
Define power
Rate at which work is done
Symbol for power
P
SI unit for power
watt (w)
Formula for power
P = w/t
If 1 joule of work is done in 1 second, how much power?
1 watt
