Chapter 5 - Work, Energy and Power Flashcards
Equation for work done?
work done= force * distance
Units for work done
J or Nm
If you hold a book, are you doing work
No.
Since there is no movement, there is no work being done. Although your hand is applying a force on the book.
If you lift a book from the ground, are you doing work
Yes.
Since there is now movement, and a force also being applied, you would be doing work.
If you drop a ball, what will happen in terms of its work
The weight of the ball will do its work. This is because the energy being transferred is to its kinetic store.
If a ball was being pushed along a ramp, from the bottom and the ramp was 0.5m high. It had a vertical length of 1.2m and an actual length of 1.3m, how would you calculate the work done? (the weight is 8N)
8 * 0.5m
Why?
Because work done is against the force of gravity, so energy is being transferred to the gravitational potential energy.
Equation to find work done at an angle
W = fx cos(theta)
Kinetic energy
Energy due to movement
Gravitational Potential Energy
Energy due to positioning of an object in the Earth;s gravitational field.
Chemical energy
Energy stored in an object as a result of reversible change in shape.
Electrical Potential Energy
Energy of electrical charges due to their position in an electric fields
Nuclear Energy
Energy within the nuclei of atoms released when the particles are rearranged.
Radiant or Electromagnetic Energy
Energy associated with all EM waves stored within the oscillating Electric and magnetic fields.
Sound Energy
Energy of mechanical waves due to the movement of atoms
Internal Energy
The sum of random potential and kinetic energies of atoms in a system
