Practical skills - paper 1 and 2

Question 1

Define an independant variable

Answer 1

The one variable that you change

Question 2

Define a dependant variable

Answer 2

The variable that you measure

Question 3

Define a control variable

Answer 3

Any variable you keep the same to make it a fair test

Question 4

Define directly proportional

Answer 4

If one variable increases the other variable increases at the same rate. eg if x doubles then y must double.

A graph would be a straight line** through the **origin

Question 5

Define inversely proportional

Answer 5

If one variable increases the other variable decreases at the same rate. eg if x doubles then y must halve

Question 6

Define an anomalous result

Answer 6

An result which does fit the pattern of trend

Question 7

What should you do if you have an anomolus result?

Answer 7

Repeat the reading

Ignore it when calculating the average

Circle on the graph and not include it in your line of best fit

Question 8

Define interval

Answer 8

The spacing between measurements eg 0, 10, 20, 30 40, 50 cm would have an interval of 10 cm

Question 9

Define range

Answer 9

The maximum and minimum values eg 0, 10, 20, 30, 40, 50 cm would have a range of 50 to 0 cm

Question 10

Define resolution

Answer 10

The smallest change that can be measured with a particular piece of equipment

Question 11

If a stop clock reads 18.72 seconds, what is its resolution?

Answer 11

0.01 s

Question 12

If a voltmeter reads 3.6 V what is its resolution?

Answer 12

0.1 V

Question 13

How can the uncertainty in a measurement be measured?

Answer 13

Half of the range

Question 14

When should you draw a line graph

Answer 14

When both variables are continuous

Question 15

When should you draw a bar graph

Answer 15

If one of the variables is discrete or categoric

Question 16

Define a continuos variable

Answer 16

Can be recored as any number eg time, mass, volume

Question 17

Define a discrete variable

Answer 17

Can be recored only as a whole number eg number of goals in a match, leaves on a plant

Question 18

Define a catergoic variable

Answer 18

Is recorded in words instead of numbers eg colours or types of metal

Question 19

Vernier calipers can measure distance to the nearest 0.01 cm. A meter ruler can measure to the nearest 0.1 cm. Which would be better for measuring the width of an object?

Answer 19

The Vernier calipers have a higher** resolution. The meter ruler has a **lower resolution. The Vernier calipers would be more accurate.

Question 20

How can you convert from cm³ into m³?

Answer 20

Divide by 1000000 (100³)

Question 21

How can you convert from mm³ into m³?

Answer 21

Divide by 1000000000 (1000³)

Question 22

Define a random error and give an example

Answer 22

A random error is an error in a measurement that is different each time. This causes points to be scattered around a line of best fit on a graph.

An example would be using a stopwatch and starting or stopping it too early

Question 23

Define a systematic (zero) error and give an example

Answer 23

An error that will be the same on all measurements. For example an electronic balance that reads 0.05 g before anything is place on it. All readings will be 0.05 g too high.

Question 24

If an electronic balance has a zero error (records a reading when it should say 0.00 ) how could this be corrected?

Answer 24

1. Reset the balance to zero
2. Record the zero error and add or subtract it from all your measurements

Question 25

What are the benefits of peer review?

Answer 25

detects false claims

detects inaccurate data

detects bias

verifies new data

Question 26

How can you check if results are precise?

Answer 26

Take repeat readings. If the results are close together then they are precise.

Question 27

What are the benefits of repeat readings?

Answer 27

Spot anomalies

Calculate an average

The average should reduce the effect of random errors.

Question 28

What is the difference between accurate readings and precise readings?

Answer 28

Accurate readings - average will be close to the true value

Precise readings - repeat readings will be close to each other