P1-Energy Stores and Systems

Question 1

Name all the energy stores

Answer 1

Thermal
Kinetic
Gravitational Potential 
Elastic Potential
Chemical
Magnetic
Electrostatic
Nuclear

Question 2

How is energy transferred?

Answer 2

Mechanically by doing work
Electrically work done by moving charges
Heating
Radiation
Between energy stores

Question 3

What is a system?

Answer 3

A single or group of objects that you are interested in

Question 4

What happens when a system changes?

Answer 4

Energy is transferred into or away from he system, between two objects or between types of energy store

Question 5

What is a closed system?

Answer 5

A system where neither matter nor energy can enter or leave

Question 6

What is the net change in a closed system?

Answer 6

The net change in the total energy of a closed system is always 0

Question 7

Describe the energy transfer of boiling a kettle

Answer 7

Energy is transferred to the water (from kettle heating element) by heating electrically into the waters thermal energy store

Question 8

What is work done?

Answer 8

Work done is another way saying energy transferred. It can be done when current flows or by force moving an object

Question 9

What happens when you throw a ball upward

Answer 9

Initial force is exerted by a person and causes work to be done, energy is transferred from the chemical store in a persons arm to the kinetic energy of the ball and arm

Question 10

What happens when a ball is dropped

Answer 10

The gravity does the work

Causes energy to be transferred from the balls gravitational energy store to its kinetic energy store

Question 11

What happens when a car brakes

Answer 11

Friction between the wheels and the brakes does work as it slows down

It causes energy transfer from the wheels’ kinetic energy stores to the thermal energy store of the surroundings

Question 12

Which store does eventually all energy end up in?

Answer 12

Thermal Store

Question 13

What way can energy use to be transferred

Answer 13

Sound waves

Question 14

If anything is moving what energy store is the energy in?

Answer 14

Kinetic

Question 15

What is the equation for working out kinetic energy

Answer 15

Kinetic Energy (joules)=

1/2 x mass (kg) x speed (m/s) squared

Question 16

If a car of a mass of 2500KG is travelling at 20 m/s calculate the kinetic energy

Answer 16

1/2 x 2500 x 20 x 20

(20 squared)

=500 000 joules

Question 17

When you lift an object work is done, where store does the energy worked go into?

Answer 17

When an object is lifted energy always goes into the gravitational potential energy store

Question 18

What is the equation for the gravitational potential energy

Answer 18

GPE=

Mass x height x gravitational field strength

Question 19

What happens when an object falls

Answer 19

Energy from the gravitational potential energy store is transferred to its kinetic energy store if there’s no air resistance. But if there is then some of the energy will also go into the thermal energy store (like in real life)

Question 20

What store is filled if an object is stretched or squashed

Answer 20

The elastic potential energy store

Question 21

What is the equation for the elastic potential energy store as long as the limit of proportionality has not been exceeded

Answer 21

Elastic potential energy=

1/2 x spring constant (N/m) x extension ^2