forces- physics

Question 1

what is the national grid and what does it do?

Answer 1

a system of transformers and cables that connects power stations to customers.

Question 2

name 2 types of transformers used in a national grid and what do they do.

Answer 2

1step-up and 2step-down

1. increase the potential difference of the electricity supply before its transmitted
2. used to bring the potential difference back down to safe

Question 3

what is charge and what is the equation for it?

Answer 3

the current flowing past a point in a given time- measured in coulombs
charge flow= current x time
Q= It

Question 4

what are the equations for 
potential difference
energy transferred 
energy transferred 
power 
power

Answer 4

pd= current x resistance V= I x weird sign
et= charge flow x pd   E= QV
et= power x time E= Pt
power= pd x current P=VI
power= current2 x resistance P= I2R

Question 5

what does alternating current (AC) and direct current (DC) mean?

Answer 5

AC= constantly changing direction- mains supply is 230V- frequency is 50 hertz (Hz) 
DC= supply by batteries and stays in 1 direction

Question 6

name the 3 types of wires, the colour and what they do- include other labels

Answer 6

live wire- red provides the potential difference from the mains
neutral wire- yellow and green, completes the circuit
earth wire- blue, stops the appliance from becoming live
fuse- breaks the circuit if a fault in an appliance causes too much current to flow.

Question 7

why might an appliance not have an earth wire?

Answer 7

doesn’t have a metal casing so there’s nothing to become live

Question 8

what is density?

Answer 8

how much mass there is in a given space (particles)

Question 9

what is the formula for density and what is its units?

Answer 9

density= mass/ volume

g/cm3 kg/m3

Question 10

how can you find the density of a regular shape?

Answer 10

weigh it and measure it with a ruler then use the equation

Question 11

how can you find the density of an irregular shape?

Answer 11

weigh it, put it in a eureka and measure the displaced water and then use the equation

Question 12

describe everything about a solid.

Answer 12

strong forces of attraction/ fixed shape/ vibrate/ high density/ close together

Question 13

describe everything about a liquid.

Answer 13

weaker forces/ irregular shape/ move past each other/ close together/ less dense than a solid/ random directions/ low speed

Question 14

describe everything about a gas.

Answer 14

no forces/ more energy/ free to move/ random directions/ high speeds/ very low densities

Question 15

what causes a build up of static?

Answer 15

friction

Question 16

what moves and what doesn’t in static electricity?

Answer 16

positive and negative electrostatic charges are produced by the movement of electrons- positive chargers don’t move.

Question 17

what does a gas do when it’s heated and how does pressure form?

Answer 17

the pressure of the gas increases if the temperature increases. the particles will collide with the sides and each other more often causing more pressure on the sides.

Question 18

what is internal energy and what happens to the internal energy when it is heated?

Answer 18

ie= the total amount of energy from kinetic and potential energy
it increases

Question 19

what is the formula for specific heat capacity and describe how it’s used.

Answer 19

trinagelE = mc triangle0

change in thermal energy (J)= mass (Kg) x shc (J/KgC) x temperature change (C)

Question 20

describe the processes of all of the changes of state.

Answer 20

solid> liquid= melting liquid> gas= boiling

gas> liquid= condensing liquid> solid= freezing