Graph Plot a graph of pressure (p), measured in kilopascals, against
Conclusion
The straight line through the origin verifies Boyle’s law: pressure is inversely proportional to volume for a fixed mass of gas at constant temperature.
Precautions After changing pressure wait a short time before taking readings to allow the temperature of the gas to return to room temperature. The increase in pressure causes an increase in temperature; as Boyle’s law states that the temperature must remain constant, time must be given for the gas to return to room temperature.
Releasing gas pressure slowly will help to ensure temperature remains constant. Avoid parallax error by reading the volume scale at eye level. Increase the range of readings to reduce percentage error. Use a syringe with a more accurate volume scale.
‘SECTION A’ EXPERIMENT QUESTIONS
Q1 A student investigated the laws of equilibrium for a set of co-planar forces acting on a metre stick. The weight of the metre stick was 1.1 N and its centre of gravity was at the 49.5 cm mark. The student applied the forces shown to the metre stick until it was in equilibrium.
3.2 N 4.7 N 1 volume a
1 Vb
, measured in cm3.
10
20
30
40
50
60
70
80
90
2.9 N Fig 4.13
(i) Describe how the student found the centre of gravity of the metre stick. (ii) How did the student know the metre stick was in equilibrium? (iii) How were the upward forces applied?
(iv) Use the data provided to verify both conditions necessary for equilibrium. (v) Suggest a reason why the centre of gravity was not at the 50.0 cm mark.
