Forces & Elasticity (AQA GCSE Physics: Combined Science)

A newton meter, as shown in Figure 1, consists of a point, connected to a metal spring.

When a force is applied to the spring, the spring stretches, and the point moves along the scale.

Figure 1

Use the information provided in the diagram to calculate the spring constant of the spring.

A student wishes to carry out an investigation to measure the spring constant of a metal spring.

Describe a method that the student could use.

Your answer should include detail of how accurate measurements may be taken and may also include a labelled diagram

The table below gives the results obtained by the student.

The student finds that after stretching, the spring does not return to its original length.

Plot a graph of force (y-axis) against extension (x-axis) on the grid below.

Mark the position of the elastic limit on the graph, using an X.

Give your reason for choosing this point.

The student has made an error whilst calculating some of the results.

Suggest what the error was and how the results could be corrected.

Use the graph to calculate the spring constant of the metal spring.

The student decided to repeat the experiment using a double spring set up, as shown in Figure 2

Figure 2

Add a line to your original graph showing the results you would expect the student to get.

You should assume that the initial extension of the springs is the same as with the original experiment.

Explain how the elastic limit of the double spring will compare with the original spring.

Figure 3 shows three different stages in a bungee jump.

Figure 3

Stage 1: The jumper is stationary and the bungee cord is slack

Stage 2: The bungee cord has no slack, but is not yet exerting a force on the jumper.

Stage 3: The jumper is at the lowest point and has temporarily stopped moving.

Describe the change in energy stores that occur between stage 1 and stage 3.

Calculate the change in the jumper’s gravitational energy store between stage 1 and stage 2.

The jumper has a mass of 60 kg (assume that the mass of the bungee cord is negligible).

Gravitational field strength = 10 N/kg

State the energy in the jumper’s kinetic store at stage 2.

Calculate the speed of the bungee jumper at stage 2.

After reaching stage 2, the bungee cord starts to stretch, exerting an upwards force on the jumper which eventually brings the jumper to a stop at stage 3.

Between stage 1 and stage 3 the jumper’s gravitational energy store decreases by a total of 18 000 joules.

State the energy in the bungee’s elastic store at stage 3.

Calculate the extension of the bungee cord at stage 3.

Using an appropriate equation from the Physics equation sheet, calculate the spring constant of the bungee cord.

You may assume that the bungee cord behaves like a perfect spring.

Use your answers to (f) and (g) to calculate the force exerted by the bungee cord on the jumper at stage 3.

At stage 3 the jumper's spine stretches a small but safe amount.

Explain why

A group of physics students are investigating force and extension of a spring.

One student obtained the results shown in Table 1.

Table 1

As the teacher came around to check the student's data, the teacher asked the student to think about why the extension data is not increasing.

Identify the mistake the student has made in their data analysis process.

Another student plotted their graph, but the shape of the curve was different to everybody else's. 

Figure 1 shows the student's graph.

Figure 1

Suggest what the student did to produce the graph shown in Figure 1.

Another student extrapolated their graph as shown in Figure 2.

Figure 2

What is the significance of the point marked X?

Tick (✓) one box.

X shows the original length of the spring
X shows the average extension of the spring
X shows the final length of the spring after deformation
X shows the increased length of the spring after deformation

Figure 1 shows a force-extension graph for a spring with a spring constant k.

Figure 1

Draw a line on Figure 1 for a spring with a higher value of k.

A force of 2 N causes a spring to extend by 3 cm.

Calculate the extension of the spring when a 3.5 N force is applied.

Give your answer in cm to 2 significant figures.

A student plotted a force-extension graph for a spring of spring constant k. 

Figure 1 shows the graph they plotted.

Figure 1

The student has labelled one of the data points as anomalous. 

State whether you agree with this choice, and explain your answer.

For the spring used in part (a), calculate the work done on the spring when a 3 N force is applied.

Give your answer in the appropriate units.