Topic 8 - Energy and Forces doing Work

Question 1

What is work done?

Answer 1

Work done is the transfer of energy when a force moves an object over a distance. It is measured in joules (J).

Question 2

What is the equation for calculating work done?

Answer 2

Work done = Force × Distance moved in the direction of the force

Question 3

What are the units of work done, force, and distance?

Answer 3

Work done: Joules (J)
Force: Newtons (N)
Distance: Meters (m)

Question 4

What is kinetic energy?

Answer 4

Kinetic energy is the energy possessed by a moving object due to its motion. It depends on the mass and speed of the object.

Question 5

What is the equation for kinetic energy?

Answer 5

Kinetic energy = 0.5 x mass x speed^2

Question 6

What is gravitational potential energy (GPE)?

Answer 6

Gravitational potential energy is the energy stored in an object due to its position in a gravitational field, usually relative to the ground.

Question 7

What is the equation for gravitational potential energy?

Answer 7

Gravitational potential energy = Mass × Gravitational field strength × Height

Question 8

What are the units for mass, gravitational field strength, and height?

Answer 8

Mass: Kilograms (kg)
Gravitational field strength: Newtons per kilogram (N/kg)
Height: Meters (m)

Question 9

What is power in physics?

Answer 9

Power is the rate at which work is done or energy is transferred. It is measured in watts (W).

Question 10

What is the equation for power?

Answer 10

Power = Work done / Time taken

Question 11

How can power be calculated using force and speed?

Answer 11

Power = Force × Speed

Question 12

What is efficiency?

Answer 12

Efficiency is a measure of how much useful energy is converted from the total energy input. It is expressed as a percentage.

Question 13

What is the equation for efficiency?

Answer 13

Efficiency = (Useful energy output / Total energy input) × 100%

Question 14

What is meant by energy dissipation?

Answer 14

Energy dissipation refers to the spreading out of energy into less useful forms, often as heat, which reduces the efficiency of energy transfer.

Question 15

What is elastic potential energy?

Answer 15

Elastic potential energy is the energy stored in an elastic object, like a spring, when it is stretched or compressed.

Question 16

What is Hooke’s Law?

Answer 16

Hooke’s Law states that the extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality.

Question 17

What is the equation for Hooke’s Law?

Answer 17

Force = Spring constant × Extension

Question 18

What are the units for the spring constant and extension?

Answer 18

Spring constant: Newtons per meter (N/m)
Extension: Meters (m)

Question 19

What happens when a material reaches its elastic limit?

Answer 19

When a material reaches its elastic limit, it no longer returns to its original shape, and permanent deformation occurs.

Question 20

What factors affect the amount of work done to overcome friction?

Answer 20

The amount of work done to overcome friction depends on the size of the frictional force and the distance over which the force acts.