Physics paper 1 and forces

Energy

Joules, J

Mass

Kg

Velocity

m/s

Gravitational field strength

N/Kg

Distance

metres, m

Power

Watts, W

Time

seconds, s

Charge

Coulombs, C

Current

Amps, A

Potential difference

Volts, V

Resistance

Ohms, $\Omega$

Force / Weight

newtons, N

Work done

Joules, J

Spring Constant

N/m

Moments

newton metres, Nm

Pressure

Pa

Area

m²

Volume

m³

Momentum

Kg m/s

Specific heat capacity

J/Kg^oC

Acceleration

m/s²

Density

Kg/m³

Activity

Becquerel, Bq

What does a scalar quantity have?

Only size no direction

What does vector quantities have?

Both magnitude and direction

Examples of scalar quantities

mass, distance, time, energy, power, speed

Examples of vector quantities.

acceleration, velocity, force

What does distance refer to?

How much ground an object has been covered in motion

What does distance refer to?

How far out object is from its starting point, overall change in position

How do you draw a vector scale diagram?

draw correct forces, measure the length of vector and and draw correct length and direction

What is Newton’s 3^rd law?

every force has an equal and opposite force

What happens when 2 forces act in the same direction on an object?

the resultant force in in the same direction

the magnitude is the sum of the forces

What happens when 2 forces act in different direction on an object?

the magnitude is the difference between the forces

What is the resultant force of a stationary object?

0

If a resultant force is applied what will happen to the object?

accelerate, or decelerate

What is Newtons 1^st law?

an object will remain at rest/constant movement unless forces to change

What happen if resultant forces are balanced?

stationary, or at constant speed

What is the turning effect of a force?

moment

What are moments measured in?

newton meters - Nm

What does a lever have to have?

fulcrum, effort, load

What is a force multiplier?

allows you to lift a heavier object with less effort

What happens when you pass power from 1 gear to another?

change direction, increase speed, increase force

What is the centre of mass?

where the mass is thought to be

How do you find the centre of mass for a regular object?

where the lines of symmetry meet

How do you find the centre of mass for an irregular shape?

suspend it and the centre of mass is bellow the suspension point

Which line does a shorter length compass go on for parallelogram of forces?

longer line

Which line does a longer length compass go on for parallelogram of forces?

shorter line

What is resolving vectors?

splitting a resulting vector into 2 components at a right angle

What is direct current?

the current that moves in only 1 direction

What is alternating current?

the current which repeatedly reverses directions

What is the a.c frequency for the UK?

50Hz

What is the rough voltage in the UK?

230v

What is a period?

the time taken for 1 wave to pass

What is the equation for frequency?

frequency = 1/period

How do you find the peak voltage?

from rest to peak

How do you measure the wavelength of 1 complete wave?

peak to peak

trough to trough

crest to crest

What is the equation for power?

power = R x I²

What colour is the live wire?

brown

What colour of the neutral wire?

blue

What colour is the earth wire?

yellow and green striped

What does the live wire do?

carries a current between negative and positive voltage

What does the neutral wire do?

completes the circuit - is kept at zero

What does the earth wire do?

current only flows through is something might become dangerous to touch - it blows the fuse (therefore, making it sae to touch)

What are the difference in the pins in a plug?

earth is longer - makes sure the appliance is earthed

live & neutral are insulated - has to be pushed all the way in

Why is wire made out of copper

good conductors

ductile (bend without breaking)

What are wires mad out of?

copper

What are pins and connectors made out of?

brass

Why is brass used for pins and connectors?

good conductor

hard wearing

What is the wire sheath made out of?

polyethene plastic

Why is the wire sheath made out of polyethene?

good insulator

can be stiff and flexible

What are the casing and wall sockets made of?

PVC

Why is PVC used for casing and wall insulators?

can be moulded

tough (doesn’t shatter)

good insulator

How do you calculate the energy transfer?

power x time

or potential difference x charge

or potential difference x current x time

Which fuses are the most common fuse?

3A and 13A

What happens to the power, if the resistance of a component increases?

increases proportionally

What happens to the power if the current increases through a component?

quadruples

What is the calculation for charge?

current x time (Q=It)

What does 1 kW equal?

1000W

What does 1 MW equal?

1,000,000W

How would you chose the fuse rating?

the next above the normal rating

What is work done to the battery equal?

energy transferred to the resistor

What is electrical power?

rate of which (electrical) energy is converted into something else

What is electrical charge measured in?

coulombs (C)

How do you find the percentage efficiency?

useful power/total power supplied x 100

What is the national grid?

a network of transformers and cables that can carry electricity

How much power does a generator in a power station produce?

25,000W

What is the typical power of a power station?

800MW

What is a step up tansformer?

increases the voltage of the electricity

What is the electricity in the national grid?

alternating current

Why is it more efficient to use a step up transformer in the national grid?

reduces power loss

What is a step down transformer?

reduces the voltage so we can use it in our homes

What is direct current?

the current that moves in only 1 direction

What is alternating current?

the current which repeatedly reverses directions

What is the a.c frequency for the UK?

50Hz

What is the rough voltage in the UK?

230v

What is a period?

the time taken for 1 wave to pass

What is the equation for frequency?

frequency = 1/period

How do you find the peak voltage?

from rest to peak

How do you measure the wavelength of 1 complete wave?

peak to peak

trough to trough

crest to crest

What is the equation for power?

power = R x I²