energy and fields

Question 1

Define energy transfer (4 pathways)

Answer 1

Energy is transferred from one store to another via 4 pathways
Heating - due to difference in temperature
Electrical - movement of charges
Propagation of waves
Mechanical - external forces are involved during energy transfer

Question 2

Define work done

Answer 2

Work done by a force on a body is defined as the product of the force and the displacement of the body in the direction of the force.

W = Fscosθ

Question 3

Define kinetic energy

Answer 3

Kinetic energy is the energy possessed by a body due to its motion. The Ek possessed by a body of mass m travelling at velocity v is given by:

Ek = 1/2 mv²

Question 4

Define the concept of a field (+ characteristics)

Answer 4

A force field is a region of space in which a body experiences a force without physical contact with another body. A force field is produced by the presence of another body.

Direction of the field = direction of the force
magnitude of field = field strength
strength of field = represented by an arrow
direction of the field = direction of the vector arrow
strength of field = spacing between the field lines (tighter = better)

Question 5

Define gravitational field

Answer 5

The gravitational field strength g at a point is the gravitiaional force per unit mass on a mass placed at the point.

Question 6

Define electric fields

Answer 6

Electric fields are produced by charges

The strength is the electric force per unit positive charge placed at that point