Physics- Forces&energy-2012

Front 1

Name the 7 principle forces

Back 1

Friction, Gravitational, Magnetic, Electrostatic, Nuclear, Elastic, Upthrust

Front 2

State 2 ways Drag is similar to friction

Back 2

1.Opposes motion
2.mainly in liquids and gases

Front 3

Friction occurs between 2 objects when 1 or both are moving, state three things

Back 3

1. Causes heat between two surfaces
2. Opposes motion
3. mainly in solids but also in liquids and gases

Front 4

Friction can be reduced by...

Back 4

Smooth surfaces
Lubrication oil

Front 5

Drag can be reduced by

Back 5

Smooth shapes
Smooth surfaces
Slower speed

Front 6

Mass is constant...

Back 6

providing no material is removed

Front 7

What is weight?

Back 7

weight is the force exerted by a mass as a result of gravity

Front 8

Formula for mass, weight, gravitationla constant

Back 8

weight = mass x gravitational constant
OR
w = m x g

Front 9

Magnetic forces act over short distances and can

Back 9

attract
repel

Front 10

Electrostatic forces are similar to magnetic forces

Back 10

act over short distances
attract
repel

Front 11

Nuclear is a very powerful force but acts over very short distances
state 2 other things

Back 11

attacts
repel

Front 12

What does nuclear force do in an atomic nucleaus?

Back 12

holds the neutrons and protons together in an atomic nucleus

Front 13

Elastic is a ..... force

Back 13

potential

Front 14

Upthrust is a force produced by different.....

Back 14

densities

Front 15

What is a balanced force?

Back 15

forces in each direction are equal

Front 16

what what is an unbalanced force?

Back 16

forces in one or more directions are not equal

Front 17

With balanced and unbalanced forces if they go in the same direction it is.... if they are going in opposite it is ....

Back 17

+, -

Front 18

What is newtons first law of motion?

Back 18

An object will remain at rest or more at constant speed if resultant force is zero (i.e balanced forces)

Front 19

What is newtons secound law of motion?

Back 19

An object will accelerate as a result of unbalanced forces

Front 20

The size of the acceleration can be calculated using:

Back 20

Force = mass x accelaration
OR
F = m x a
F=ma

Front 21

The statement for terminal velocity

Back 21

When an object falls in a gas or liquid it will eventually reach a terminal velocity

Front 22

Terminal velocity is when

Back 22

forces are balanced
speed is constant

Front 23

What are the 5 stages of free fall?

Back 23

1. leave plane & start accelerating
2. reach terminal velocity
3. open parachut start decelerating
4. secound terminal velocity
5. land safely

Front 24

work is done when a force...

Back 24

moves

Front 25

what is work also?

Back 25

work is also a measure of the energy transferred to change in energy from one form to another

Front 26

Work is calculated using

Back 26

work = force x distance moved by force
OR
w = F x d

Front 27

With the work formula what is each one measurd in
1. work
2. force
3. distance moved by force

Back 27

1. joules (J)
2. newtons (N)
3. metres (m)

Front 28

work is....... of time

Back 28

independant

Front 29

what is gravitaional potential energy?

Back 29

GPE is the energy an object has because of its height in a gravitational field

Front 30

To lift an object we have to..

Back 30

use a force to overcome the effects of gravity

Front 31

GPE is a special case of work and so the formula is

Back 31

Gravitaional potential energy = mass x gravity x height
OR
GPE - m x g x h

Front 32

In GPE what are the following measured in
1. mass
2. gravitational constant measurement
3. height
4. GPE

Back 32

1. kilograms (kg)
2. metres per secound squared (m/s²)
3. metres (m)
4. Joules (J)

Front 33

What is kinetic energy?

Back 33

Kinetic energy is the energy of an object due to motion

Front 34

Kinetic energy depends on both....

Back 34

the mass of an object
the speed or velocity of an object

Front 35

The formula for kinetic energy is:

Back 35

Kinetic energy - ½ x mass x velocity squared
OR
KE = ½ x m x v²

Front 36

State 2 things about power and work

Back 36

work tells us the energy transferred
powers tells us how quickly work is done

Front 37

Formula for power

Back 37

power = work done / time
OR
p = w / t

Front 38

the power formula what are the following measured in
1. power
2. work
3. time

Back 38

1. watts (w)
2. Joules (J)
3. secounds (s)

Front 39

Forces can cause objects to........

Back 39

deform or change shape

Front 40

If when the force is removes, an object returns to its original shape we call this....

Back 40

ELASTIC deformation

Front 41

If the change is permenant on an object we call this

Back 41

PLASTIC deformation

Front 42

What is Hooke's law?

Back 42

Hooke's law states that providing a wire or spring remains within its elastic limits extension is driectly proportional to force that produces it

Front 43

Hooke's law formula:

Back 43

force = spring constants x spring extension
OR
F = K x X

Front 44

Springs obey hooke's law providing......

Back 44

within elastic limit

Front 45

What do springs in series do?

Back 45

Springs in series decrease the spring constant compared to a single spring

Front 46

Springs in series do 2 things

Back 46

produces greater extension/ force
less steep gradient than single spring

Front 47

What do springs in parallel do?

Back 47

Springs in parrallel increase the spring constant compared to a single spring

Front 48

Springs in parrallel do 2 things

Back 48

Produces less extension / force
steeper gradient than single spring

Front 49

Which 2 materials do not obey hookes law?

Back 49

rubber
polymers ( i.e polythene)

Front 50

what is the structure of natural rubber and many polymers like?

Back 50

a pile of worms