PAGs paper 3

Question 1

how can we measure mass

Answer 1

use a digital balance

Find the mass of the container, then the total mass and take them away

Question 2

how can we measure volume in a liquid

Answer 2

use a measuring cylinder

Question 3

how can we measure volume of a regular solid

Answer 3

use the measurements

Question 4

how can we measure volume of an irregular solid

Answer 4

pour a known amount of water into a eureka can until it is dripping and allow any excess water to drip out till it stops
Put in the solid and then allow water to be collected in a measuring cylinder or beaker
Take this away from the original known volume of water

Question 5

How to improve accuracy in measure volume

Answer 5

repeat

use vernier calipers (better rulers)

Question 6

safety in measuring volume

Answer 6

keep the water away from the mass balance

mop up water if you drop it

Question 7

method for the Hooke’s Law

Answer 7

1. attach a spring to a clamp and let the spring hand freely over the bench
2. Measure the length of the spring with no weights
3. Slowly add masses to it
4. Measure the length of the spring
5. Take this way from the original length to find the extension
6. repeat and record results

Question 8

safety for hooke’s law

Answer 8

1. wear ere protection
2. make sure the clamp is securely fixed
3. don’t make the masses bounce
4. be careful that masses don’t fall onto feet

Question 9

Equipment for measuring acceleration

Answer 9

trolley
piece of card
ramp 
ruler 
blocks to raise the ramp
light gates and a data logger 
clamp and clamp stand

Question 10

method for measuring acceleration

Answer 10

1. raise the ramp using block and set up light gates on the lower end, connected to a data logger. Attach a card on the car
2. Measure the distance of the ramp
3. Let the trolley roll down the ramp from the top .
4. when the card interrupts the beam, there will be a time
5. use this data to find speed
6. vary and blocks and find results

Question 11

safety for measuring acceleration

Answer 11

runway may be heavy so may need 2 people to carry it

make sure the trolley doesn’t roll off the bench

Question 12

parallel circuit

Answer 12

pd stays the same
current adds up
if u add another lamp the total current decrease and the net resistance decreases

Question 13

series circuit

Answer 13

current is the same
pd across each component adds up to the pd near the battery
if you add another lamp the current decreases and the net resistance increases

Question 14

safety cautions when working with circuits

Answer 14

filament bulbs may get hot so dont touch them
avoid short circuits
keep water away

Question 15

filament lamp circuit components

Answer 15

as pd increases, current increases at a decreasing rate

The electrons in the wire collide with ions, that vibrate more as the wire gets hotter, meaning more collisions

Question 16

Resistor circuit components

Answer 16

Resistance stays constant
pd increases as current does
linear circuit element

Question 17

Diode circuit components

Answer 17

Only allows current in the positive direction

Resistance is decreasing as they are inversely proportional

Question 18

Equipment for measuring SHC

Answer 18

1kg metal block with 2 holes 
low voltage heater in the block 
Low voltage power supply 
thermometer in block 
ammeter
thermal insulation around block

Question 19

Method for measuring SHC

Answer 19

1. place the thermometer in the aluminium block and measure the starting temperature
2. turn on the joulemeter and measure the starting energy
3. switch on the power pack for 5 or so minutes
4. measure the joulemeter reading and the temperature (measure its highest temperature as it might still keep climbing)

Question 20

improving accuracy with SHC

Answer 20

Repeat
Insulate the block to reduce heat dissipation
Put oil in the hole to make it conduct electricity
Think about the height of the heater coming out of the block

Question 21

Safety with SHC

Answer 21

Don’t touch the heater after its been turned off
NOT WITH WET HANDS
Switch off the heater if it’s burning