Read the scale — questions

1. state / explain

A pupil measures a key with a ruler whose end is worn. One end of the key lines up with the 1.0 cm mark and the other end with the 6.4 cm mark. Choose the length of the key. Then explain why the pupil did not put the key at the very end of the ruler.

Circle one answer.

• 6.4 cm
• 5.4 cm
• 7.4 cm
• 6.4 mm

Why not start at the end of the ruler?

Nudge (only if you are stuck): The key does not start at zero. What do you do with the 1.0 cm?

2. calculate

A stack of 40 identical coins is 8.0 cm tall. Calculate the thickness of one coin, in millimetres, to 2 significant figures.

Thickness of one coin: ______________ unit ________

Nudge (only if you are stuck): First change 8.0 cm into millimetres. The stack is 40 coins thick, so share that height between them.

3. identify / state

A measuring cylinder of water stands on a flat bench. Where should your eye be when you read it, and which part of the water surface do you read? Then name the error that this eye position avoids.

Circle one answer.

• Eye level with the surface; read the bottom of the meniscus
• Eye above the surface; read the bottom of the meniscus
• Eye level with the surface; read where the water touches the glass
• Eye below the surface; read the middle of the curve

Which error does this avoid?

Nudge (only if you are stuck): The water surface curves up at the glass. Which part of the curve is level with the true reading?

4. calculate

A pupil stacks 250 identical sheets of card and squeezes them flat. The stack is 4.0 cm thick. Calculate the thickness of one sheet, in millimetres, to 2 significant figures.

Thickness of one sheet: ______________ unit ________

Nudge (only if you are stuck): Change 4.0 cm into millimetres first. Then share it between the sheets.

5. state

A 50 cm³ measuring cylinder is marked every 1 cm³. With your eye level with the water, the bottom of the meniscus is on the 32 cm³ mark and the edges of the surface climb the glass to the 33 cm³ mark. State the volume of the water, and the smallest division of the scale.

Volume of the water / cm³

Smallest division / cm³

Nudge (only if you are stuck): Which part of the curved surface gives the reading? What is the gap between two neighbouring marks?

6. explain

Explain why measuring 100 sheets of paper and dividing by 100 gives a better value for the thickness of one sheet than measuring one sheet with a ruler.

Nudge (only if you are stuck): Compare the thickness of one sheet with the smallest division of the ruler. What happens to a reading error when you divide by 100?

7. calculate / describe

To find the diameter of a thin wire, a pupil winds it tightly round a pencil so that 30 turns sit side by side, touching. The coil measures 1.5 cm along the pencil. (a) Calculate the diameter of the wire in millimetres. (b) Describe one way to make the measurement of the coil’s length as accurate as possible.

(a) Diameter of the wire / mm, with working

(b) One way to make the coil’s length accurate, and why

Nudge (only if you are stuck): Each turn adds one diameter to the length of the coil. How many diameters are in 1.5 cm?