Practise selecting balances to measure mass and distinguishing valid mass comparisons from changes caused by gravity, free-fall acceleration or object size.
Two rectangular blocks consist of different materials.
Four different methods are suggested to compare the two masses.
1 Compare the accelerations with which they fall freely.
2 Compare the values of their lengths × breadths × heights.
3 Hang each in turn from the same spring. Compare the extensions.
4 Place one in the right-hand pan of a beam balance and the other in the left-hand pan.
Which methods give a comparison of the two masses?
1, 2 and 3
1 and 2 only
3 and 4 only
4 only
C