6.1.1 Energy Stores and Systems

Question 1

What is a system?

Answer 1

an object or a group of objects.

Question 2

What happens when a system changes?

Answer 2

The way energy is stored will change.

Question 3

What are the eight types of energy store?

Answer 3

Chemical
Gravitational
Elastic
Nuclear
Electrostatic
Magnetic
Kinetic
Thermal

Question 4

What are the energy transfers in when a ball is thrown up in the air and reaches its highest point?

Answer 4

Chemical in a human;
becomes kinetic in the ball;
which turns to gravitational in the ball as it gets higher

Question 5

What is needed for a complete description of a system?

Answer 5

The object or groups of objects

The type of energy being stored

Question 6

What is needed when talking about a change in a system?

Answer 6

A starting point and a end point.

Question 7

What are the energy transfers in when a pen is dropped in the desk?

Answer 7

gravitational in the pen;
becomes kinetic in the pen as it falls;
which becomes thermal in the pen and surroundings

Question 8

What are the energy transfers in when a wind up toy is released?

Answer 8

Elastic energy in the spring;

becomes kinetic energy in the toy

Question 9

What is meant by the term conservation of energy?

Answer 9

Energy cannot be created or destroyed;

only transferred between systems and stores.

Question 10

What is energy measured in?

Answer 10

Joules (J)

Question 11

If 120 joules of energy input in to a system, how many joules will be output?

Answer 11

The same number. 120 joules

Question 12

What do we often call energy that has been dissipated in a less useful way?

Answer 12

It has been wasted.

Question 13

What is the equation relating work done, force and distance?

Answer 13

work done = force x distance moved in the direction of the force.

Question 14

What is the unit of force?

Answer 14

Newtons (N)

Question 15

What is the unit of distance?

Answer 15

Metres (m)

Question 16

What happens when a force causes an object to move a distance?

Answer 16

Work is done;

energy is transferred.

Question 17

What is the relationship between work done and energy transferred?

Answer 17

Work done = energy transferred.

Question 18

How do we define 1 joule?

Answer 18

1 joule of work is done when a force of 1 N causes a displacement of 1 m.

Question 19

What happens when work is done against friction?

Answer 19

A object or system gains energy in the thermal store;

the object gets hotter/its temperature increases.

Question 20

What is the equation relating gravitational energy, height, mass and g?

Answer 20

Gravitational energy = mass x g x height

GE = mgh

Question 21

When an object is dropped, what happens to the amount of gravitational energy it has?

Answer 21

The gravitational energy decreases;

as the change in height is negative

Question 22

What is the unit of mass?

Answer 22

Kilograms (kg)

Question 23

When dealing with mass, which unit should we use?

Answer 23

Kilograms (kg)

Question 24

What is the unit of height?

Answer 24

Metres (m)

Question 25

What is the equation relating kinetic energy, mass and speed?

Answer 25

Kinetic Energy = 1/2 x mass x (speed)2

KE = 1/2mv2

Question 26

When an object is dropped how much gravitational and kinetic energy will it have?

Answer 26

Gravitational energy is maximum

Kinetic energy is zero (it is not moving)

Question 27

Just before an object hits the group how much gravitational and kinetic energy will it have?

Answer 27

Gravitational energy is zero (the height is zero)

Kinetic energy is maximum (it is moving at its maximum speed)

Question 28

What happens to the kinetic energy in an object when it hits the ground?

Answer 28

It is dissipated as thermal.