4. Energy and Fields

Question 1

eqn for work done

Answer 1

W=Fscosθ

Question 2

eqn for kinetic energy

Answer 2

E.K=1/2 mv^2

Question 3

work done by a force

Answer 3

the product of the force and displacement in the direction of the force

Question 4

gravitational field strength at a point

Answer 4

the gravitational force per unit mass on a mass placed at that point

Question 5

electric field strength at a point

Answer 5

the electric force per unit charge on a positive charge placed at that point

Question 6

eqn for gravitational potential energy

Answer 6

E.P =mgh

Question 7

gravitational potential energy store, electric potential energy store and elastic potential energy store (nr)

Answer 7

• energy store for a mass due to its position in a gravitational field
• the energy store for a charged body due to its position in an electric field
• the energy store in an elastic body due to its elastic deformation

Question 8

eqn for elastic potential energy

Answer 8

F=1/2kx^2

Question 9

principle of conservation of energy eqn

Answer 9

initial total mechanical energy + work done by external forces = final total mechanical energy

Question 10

power

Answer 10

power is defined as the rate of energy transfer

Question 11

Eqn for power

Answer 11

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Question 13

At max speed,

Answer 13

Forward force=drag force