Practise Edexcel A-Level Physics processing-results skills through processed columns, graph plotting, gradient constants, percentage uncertainty and consistency checks.
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.
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
Concrete is often used to make supporting beams in buildings.
Strands of a material can be added to the concrete mix to produce fibre-reinforced concrete.
A student had some small beams made of fibre-reinforced concrete.
Each beam was the same size.
He placed a beam across two supports, as shown.
The student repeated the experiment using beams that contained different masses of reinforcing fibres. The student's results are shown in the table.
The student concluded that the increase in maximum force was proportional to the mass of fibre in the beam.
Explain how the student could justify his conclusion.
A student used a laser and screen to determine the diameter of a hair. The apparatus was arranged as shown.
The student placed the screen 2 m from the hair.
He switched on the laser. A diffraction pattern was produced on the screen, as shown.
Explain how the student could modify the arrangement of the apparatus to reduce the percentage uncertainty in this value.
The student repeated the procedure using three different lasers. Each laser produced a different wavelength of light.
The student calculated the diameter d of the hair using each laser. He recorded the values as shown.
Determine the percentage uncertainty in the mean value of d.
Percentage uncertainty =
In a different experiment, the student applied force to stretch the hair. He determined the average breaking stress for hair as 181 MPa with a percentage uncertainty of 6\%.
The student suggested that the breaking stress for hair is the same as the breaking stress for copper wire.
Deduce whether the suggestion is correct.
breaking stress for copper wire =210 MPa
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.
Using the grid opposite, plot a graph of d on the y-axis against F on the x-axis.
A student used a laser and screen to determine the diameter of a hair. The apparatus was arranged as shown.
The student placed the screen 2 m from the hair.
He switched on the laser. A diffraction pattern was produced on the screen, as shown.
Explain how the student could modify the arrangement of the apparatus to reduce the percentage uncertainty in this value.
A student determined a value for the acceleration of freefall g using the apparatus shown.
In this investigation, the relationship between t and h is given by
1/t² = (g/3s²)h − R
where R is a constant.
where R is a constant.
where R is a constant.
The student determined the value of g as with a percentage uncertainty of 4%.
Deduce whether the student's value of g is consistent with the accepted value.
A strain gauge is a sensor made from metal foil fixed to a plastic sheet, as shown.
Bending the plastic sheet changes the dimensions of the metal foil.
This changes the resistance of the metal foil.
A student connected the strain gauge into the circuit shown below.
The student switched on the power supply and the voltmeter displayed the following reading: 16.2 mV.
Determine the percentage uncertainty in this reading.
Percentage uncertainty =