Practise Edexcel A-Level Physics AS Unit 3 Practical Skills I with graph plotting, experimental methods, uncertainty and data criticism.
A student is investigating the effect of temperature on the viscosity of oil by measuring how fast the oil flows through a funnel. He uses the apparatus shown.
State a piece of apparatus the student could use to vary the temperature of the oil.
State a piece of apparatus the student could use to measure the time taken for the oil to flow through the funnel.
The two thermometers shown below are available.
He chooses to use the digital thermometer.
Justify his choice.
Identify one control variable in this investigation.
Describe how this variable can be controlled.
The student initially measures the time from starting to pour the oil into the funnel to the last drop of oil falling from the funnel.
State how the rate of flow of the oil should be calculated.
Describe how the same apparatus could be used to calculate a more accurate value for the rate of flow of the oil.
A student slid a small metal cube down a frictionless ramp. The cube collided with a fixed metal block at the bottom of the ramp.
The student released the cube from position X as shown in the diagram. After the collision, the cube rebounded to position Y.
The student measured heights h and r. He then repeated the experiment using several different starting positions.
The student recorded his results in the table below.
h / m | r / m
0.20 | 0.11
0.25 | 0.137
0.30 | 0.16
0.35 | 0.19
0.40 | 0.217
0.45 | 0.24
Criticise these results.
Plot a graph of r on the y-axis and h on the x-axis.
Graph grid for plotting r against h
The coefficient of restitution e is given by the equation
e = v/u
where v is the velocity of the cube immediately after the collision.
Explain why the gradient of the graph is e².
A student made measurements on the solid metal prism shown.
The student used a balance to determine the mass of the metal prism.
The reading on the balance is shown below.
State the resolution of the balance.
Determine the percentage uncertainty in this reading.
Percentage uncertainty =
The student used vernier calipers to determine the lengths a, b and c.
Explain one technique he should use to determine accurate values for these lengths.
The percentage uncertainty in this calculated value of the density of the metal is 0.9%.
The accepted value for the density of copper is 8.94 g cm^{-3}.
Deduce whether the prism could be made of copper.
A student investigated the bending of a plastic beam.
The beam, of width w and height h, was supported at either end by two metal rods a distance l apart, as shown.
She applied a force F to the middle of the plastic beam by hanging a mass from it.
The beam bent downwards as shown.
She measured the vertical distance d moved by the middle of the plastic beam and repeated this measurement for increasing values of F.
She recorded her results in a table, as shown.
Criticise the recording of these results.
Using the grid opposite, plot a graph of d on the y-axis against F on the x-axis.
Determine the gradient of your graph.
Gradient =
The student recorded the following measurements for the plastic beam.
l / cm = 30
w / mm = 20
h / mm = 10
Determine E, in GPa, for the plastic beam.
E = GPa
The student suggested repeating the investigation using a glass rod instead of a plastic beam.
Explain a safety issue that would be caused by using a glass rod.
