Units, measurements and working safely

Question 1

What must you always do when something is measured

Answer 1

State the units

Question 2

Variable = Length

Answer 2

Measuring device used = Ruler, Tape measure, trundle wheel Units = meter (m), kilometer (km), mentimetre (cm), millimetre (mm)

Question 3

Variable = Volume of liquid

Answer 3

Measuring device used = Measuring cylinder Units = Milliliters (ml), Liters (L)

Question 4

Variable = Mass

Answer 4

Measuring device used = Balance Units = gram (g), kilogram (kg)

Question 5

Variable = Temperature

Answer 5

Measuring device used = Thermometer Units = Degree Celsius (C)

Question 6

Variable = Force

Answer 6

Measuring device used = Force meter (newton spring balance) Units = Newton (N)

Question 7

Give examples of safety rules when doing an experiment

Answer 7

• Wear goggles or safety glasses, especially when handling or heating chemicals. - Wash your hands after handling chemicals, animals, plants, soils, etc. - Wipe up any spills immediately. - Never leave a flame, such as a candle or a Bunsen burner, unattended.

Question 8

What units would be most appropriate to use to measure the following items? Mass of an Apple?

Answer 8

grams

Question 9

Volume of a solution or liquid?

Answer 9

ml

Question 10

Force taken to lift a pencil case ?

Answer 10

N

Question 11

Width of the classroom

Answer 11

m

Question 12

Length of a ladybird

Answer 12

mm

Question 13

Peter is given two force meters. One measures from 0 – 10 N and one measures from 0 – 100 N. Which should he choose to measure as accurately as possible the force taken to pull a block (roughly 9 N)? explain

Answer 13

1 ) 0 - 10N 2) This scale will give a more accurate measurement because it is a smaller and more accurate scale size

Question 14

Read the values

Answer 14

4.7

Question 15

Read the value

Answer 15

52

Question 16

What is a fair test

Answer 16

In a fair test you need to :

a) change one variable,
b) measure one variable and
c) keep all of the other variables the same.

Question 17

What is a control?

Answer 17

In some investigations we have one part of the experiment that will be used as a comparison with the results of other parts.

e.g seed germination

where a control set of seeds is grown with water, oxygen,warmth and light

Question 18

It is a good idea to repeat readings when doing an investigation?

Answer 18

Yes -

This allows you to check your results to see if they are reliable (repeatable). And so this is better than one single reading.

Question 19

What key things do you need to think about when planning an investigation?

Answer 19

• what would be changed (independent variable) • what would be measured (dependent variable) • any key variables to be controlled
• what apparatus you would use and how (but keep it brief).

Question 20

Rebecca wants to find out whether the floor surface affects the distance travelled by a toy car after it has run down a ramp.

What is the independent variable in her investigation (= what will she change)?

Answer 20

Independent variable is = Floor surface

Question 21

Rebecca wants to find out whether the floor surface affects the distance travelled by a toy car after it has run down a ramp.

What is the dependent variable in her investigation (= what will she measure)?

Answer 21

Dependent variable = Distance travelled by the car

Question 22

Rebecca wants to find out whether the floor surface affects the distance travelled by a toy car after it has run down a ramp.

Suggest two things she would need to keep the same to make it a fair test. (Remember to focus on things that would affect the result.)

Answer 22

1) Same toy car
2) Same ramp

Question 23

Tamal wants to find out if the size of sugar crystals affects how quickly they dissolve. He puts the sugar into a beaker of water. He stirs the mixture and uses a timer to find out how long the sugar takes to dissolve.

What would Tamal need to do to make this a fair test? 4 marks

Answer 23

1) Same amout of water
2) same sugar
3) same temperature
4) stir at same speed

Question 24

Describe how you could carry out an investigation to find out whether the length of people’s legs affects how quickly they can run? 4 marks

Answer 24

talk about same surface, distance, shoes, stopwatch

Question 25

Some children want to make a catapult. They have some different widths of elastic and they want to find out which is best for the catapult.

(a) What might they choose as their dependent variable?

Answer 25

Dependent variable = distance of the stone thrown

Question 26

Some children want to make a catapult. They have some different widths of elastic and they want to find out which is best for the catapult.

(a) If they choose this variable, what question are they investigating?

Answer 26

If the width of the elastic affects how far a stone can be flung.

Independent variable = width of elastic