Energy stores and systems

Question 1

What is the formula for kinetic energy

Answer 1

1/2 x mass x v2

Question 2

What is a system

Answer 2

A single or group of objects that your interested in

Question 3

What is a closed system

Answer 3

Systems where neither matter nor energy can leave

Question 4

How is heat energy stored

Answer 4

By heating an object you are transferring thermal energy into it

Question 5

What is the energy transfer when chucking a ball

Answer 5

Chemical energy store in the arm transferred into a kinetic store into the ball

Question 6

When a ball is dropped what is the energy transfer

Answer 6

Gravitational energy store becomes a kinetic energy store

Question 7

Energy transfer when a car breaks

Answer 7

Kinetic energy from the breaking of the car to thermal energy from the tires which dissipates into the surroundings

Question 8

Elastic potential energy store

Answer 8

Stretching or squashing an object can transfer energy to it’s elastic potential store

Question 9

What is the conservation of energy prinicple

Answer 9

Energy can never be created or destroyed but can be transferred from one system to another

Question 10

What is the equation for power

Answer 10

Power= energy / time

Or

Power= work/time

Question 11

Define power

Answer 11

Either the rate of energy transfer or the rate of work done

Question 12

What is conduction

Answer 12

The process of vibrating particles transferring energy to neighbouring particles

Question 13

How is energy transferred by conduction

Answer 13

Particles in the object which are being heated collide with each other . These collisions cause cause energy to be transferred between partcilez

Question 14

What is thermal conductivity

Answer 14

Measure of how quickly energy is transferred through a material in conduction

Question 15

What is convection

Answer 15

Energetic particles move away from hot regions too cooler regions

Question 16

Convection occurs in liquid and gases because …

Answer 16

Their particles are allowed to move around . When you heat these particles the vibrations cause further distance between them.

Question 17

Insulation examples

Answer 17

Cavity walls- a gap between inner and outer walls . The air gap in the middle reduces the amount of energy transferred by conduction through the walls

Double glazer windows- gap between to widow panes . The air gap reduces heat loss

Question 18

Thermal insulator PRACTICAL

Answer 18

Boil water in kettle . Pour water into a container measuring the volume of water

Use a thermometer to measure it’s initial temp

Seal the container for 5 minutes . Use a stopwatch

Remove the lid measure final temperature

Repeat experiment but use different materials . Testing how effective they are as insulators .

The lower the temperature difference the better the insulator

Question 19

Efficiency equations

Answer 19

Either

Useful power output/ total power input

Or

Useful output energy transfer / total input energy transfer

Question 20

Equation for work done

Answer 20

Force x distance

Joules

Question 21

Kinetic energy

Answer 21

1/2 x mass x velocity2

Joules

Question 22

Gravitational potential energy

Answer 22

Mass x gravity x height

Or

Weight x height

Question 23

Power

Answer 23

Energy/time

WATTS

Question 24

efficiency

Answer 24

Useful energy out / total input

Question 25

The rate of energy transfer from a house can be reduced by …

Answer 25

Having walls with a low conductivity.

Question 26

What unit is the joule equivalent to

Answer 26

NM

Question 27

True or false ? If somethings moving there must be an overall resultant force

Answer 27

False