1.4 Energy concepts

Question 1

Work definition

Answer 1

Work done by a force is the product of the magnitude of the force and the distance moved in the direction of the force.( W.D. = Fxcos θ )
Unit: J

Question 2

Principle of conservation of energy

Answer 2

Energy cannot be created or destroyed, only transferred from one form to another. Energy is a scalar.

Question 3

Potential energy, Ep

Answer 3

This is energy possessed by an object by virtue of its position. (in a gravitational field) Ep = mgh Unit: J

Question 4

Kinetic energy, Ek

Answer 4

This is energy possessed by an object by virtue of its motion. Ek = 1⁄2mv2 Unit: J

Question 5

Elastic potential
energy

Answer 5

This is the energy possessed by an object when it has been deformed due to forces acting on it.
Eelastic = 1⁄2 Fx or 1⁄2 kx2 Unit: J

Question 6

Energy

Answer 6

The energy of a body or system is the amount of work it can do. Unit: J

Question 7

Power, P

Answer 7

This is the work done per second, or energy transferred per second. Unit: W [= J s-1]