a
Weight of pen
Weight = mg seen or used
[ignore power of 10 error]
Answer [ 0.11 N]
Eg Weight = 0.011 kg x 9.81 m s-2
= 0.108 N
2 marks
bi
Add labelled arrow to represent weight
Arrow pointing down at 8 cm labelled weight (of pen) /0.11 N /W/mg /their value
[Check by eye. Arrow will be along the vertical line of the last letter ‘d’ in the word
‘balanced’ in the line above]
1 mark
bii
Calculate weight of top(ecf their value of weight)
Use of principle of moments i.e. a clockwise moment equal to an anti-clockwise moment
[Give this mark even if distances are wrong, but must use 0.11 N / their value]
Correct distances used [must be 1 cm and 4cm, no ECF from bi]
Answer [ 0.03 N ]
Eg 0.11 N x 1 cm = W x 4 cm
W = 0.0275 N
[Only penalise same unit error once]
3 marks
