Forces & elasticity

A student investigated how the force applied to a spring affects the length of the spring.

Figure 13 shows the apparatus used.

What is the independent variable in this investigation?

Describe one risk of harm in this investigation and a safety precaution to reduce the risk.

Safety precaution

The student measured the length of the spring using the arrangement shown in Figure 13.

Give two ways the student could have changed the arrangement to improve the accuracy of the measurement.

The student recorded accurate values for the length of the spring as the mass on the spring increased.

The student calculated the force applied to the spring by each mass.

Figure 14 shows the results.

Why does the line on the graph not pass through the origin?

Above 6.0 N the line on Figure 14 curves upwards.

Explain why.

Use the Physics Equations Sheet to answer questions 09.6 and 09.7.

Which equation links extension (e), force (F) and spring constant (k)?

Tick (✓) one box.

When the force on the spring is 4.0 N, the extension of the spring is 0.064 m.

Calculate the spring constant of the spring.

A student investigated how the force applied to a spring affects the length of the spring.

Figure 1 shows the apparatus used.

What is the independent variable in this investigation?

Describe one risk of harm in this investigation and a safety precaution to reduce the risk.

Safety precaution

The student measured the length of the spring using the arrangement shown in Figure 1.

Give two ways the student could have changed the arrangement to improve the accuracy of the measurement.

The student recorded accurate values for the length of the spring as the mass on the spring increased.

The student calculated the force applied to the spring by each mass.

Figure 2 shows the results.

Why does the line on the graph not pass through the origin?

Above 6.0 N the line on Figure 2 curves upwards.

Explain why.

Use the Physics Equations Sheet to answer questions 02.6 and 02.7.

Which equation links extension (e), force (F) and spring constant (k)?

Tick () one box.

When the force on the spring is 4.0 N, the extension of the spring is 0.064 m.

Calculate the spring constant of the spring.

A swimming pool is being filled with water.

Calculate the weight of the water in the swimming pool when the mass of the water is 25 000 kg.

gravitational field strength = 9.8 N/kg

Use the equation:

weight = mass × gravitational field strength

When the swimming pool is full, the weight of the water is 1 960 000 N.

The bottom of the swimming pool has an area of 49 m².

Calculate the pressure at the bottom of the swimming pool when it is full.

Use the equation:

Choose the unit from the box.

There is a force acting on the side of the swimming pool because of the water pressure.

Figure 11 shows the side of the swimming pool.

Which arrow shows the direction of the force acting on the side of the swimming pool?

Tick (✓) one box.

A child is swimming in the pool. The velocity of the child is 0.70 m/s.

The child then accelerates for 5.0 s, reaching a final velocity of 1.3 m/s.

Calculate the acceleration of the child.

Use the equation:

Figure 12 shows a diving board at the side of the swimming pool.

The original length of the spring is 0.84 m.

When the child stands on the diving board, the length of the spring decreases by 0.21 m.

Calculate the percentage change in the length of the spring.

Use the Physics Equations Sheet to answer questions 07.6 and 07.7.

Write down the equation which links extension (e), force applied to a spring (F) and spring constant (k).

The force applied to the spring by the weight of the child is 336 N.

The change in length of the spring is 0.21 m.

Calculate the spring constant of the spring.

The child steps off the diving board and falls into the swimming pool.

The initial velocity of the child is 0 m/s.

acceleration due to gravity = 9.8 m/s²

Calculate the final velocity when the child has fallen a distance of 0.95 m through the air.

Give your answer to 2 significant figures.

Use the Physics Equations Sheet.

A student carried out an investigation to determine the spring constant of a spring. Figure 1 shows the spring before and after a mass was hung from the end of the spring.

What is the extension of the spring in Figure 1 ? Tick (✓) one box.

Give one safety precaution the student should have taken during this investigation.

The student hung a mass of 0.050 kg from the spring. gravitational field strength = 9.8 N/kg Calculate the weight of the 0.050 kg mass. Use the equation: weight = mass × gravitational field strength

The weight of the mass applies a force to the spring. The student added more masses and recorded the extension of the spring. Which graph in Figure 2 shows the relationship between the force applied to the spring and the extension of the spring? Tick (✓) one box.

A force of 2.0 N was applied to a different spring. The extension of the spring was 0.080 m. Calculate the spring constant of the spring. Use the equation:

Tick (✓) one box.

The relationship between weight and mass for an object can be written as:

Which sentence describes the relationship between weight and mass?

Tick (✓) one box.

Figure 7 shows a balance used to measure the mass of 5 oranges.

All 5 of the oranges have the same mass.

Determine the mass of 1 orange.

Calculate the weight of 1 orange.

gravitational field strength = 9.8 N/kg

Use the equation:

weight = mass × gravitational field strength

The balance shown in Figure 7 contains a spring.

Figure 8 shows the spring with no force acting on it and with a force of 6.0 N acting on it.

Tick (✓) one box.

Use the equation:

What will happen to the spring when the force is removed?

Figure 9 shows a balance used to measure the mass of five tomatoes.

What is meant by ‘centre of mass’?

Calculate the mean weight of a tomato in Figure 9.

Use the Physics Equations Sheet.

gravitational field strength = 9.8 N/kg

The balance in Figure 9 contains a spring that compresses when the tomatoes are placed on the balance.

Figure 10 shows the spring with no force acting and with a 6.0 N force acting.

Determine the spring constant of the spring.

Use the Physics Equations Sheet.

Explain one property of the spring that makes it suitable for use in the balance.

Figure 20 shows a child on a playground toy.

The springs have been elastically deformed. Explain what is meant by ‘elastically deformed’.

A student investigated the relationship between the force applied to a spring and the extension of the spring. Figure 21 shows the results.

Describe a method the student could use to obtain the results given in Figure 21. You should include a risk assessment for one hazard in the investigation. Your answer may include a diagram.

Which equation links extension (e), force (F) and spring constant (k). Tick (✓) one box.

Figure 21 is repeated below.

Determine the spring constant of the spring. Use Figure 21.

The student concluded: ‘The extension of the spring is directly proportional to the force applied to the spring.’ Describe how Figure 21 supports the student’s conclusion.

The student repeated the investigation using a different spring with a spring constant of 13 N/m. Calculate the elastic potential energy of the spring when the extension of the spring was 20 cm. Use the Physics Equations Sheet.

Figure 3 shows a child on a playground toy.

The springs have been elastically deformed. Explain what is meant by ‘elastically deformed’.

A student investigated the relationship between the force applied to a spring and the extension of the spring. Figure 4 shows the results.

Describe a method the student could use to obtain the results given in Figure 4. You should include a risk assessment for one hazard in the investigation. Your answer may include a diagram.

Which equation links extension (e), force (F) and spring constant (k). Tick (✓) one box.

Figure 4 is repeated below.

Determine the spring constant of the spring. Use Figure 4.

The student concluded: ‘The extension of the spring is directly proportional to the force applied to the spring.’ Describe how Figure 4 supports the student’s conclusion.

The student repeated the investigation using a different spring with a spring constant of 13 N/m. Calculate the elastic potential energy of the spring when the extension of the spring was 20 cm. Use the Physics Equations Sheet.

A student placed a magnet on top of a plastic support in a bowl of water. This magnet was fixed in position and above the surface of the water. The student put a second magnet into a piece of cork so that the magnet floated on the water. Only the north pole of the floating magnet was above the surface of the water. Figure 6 shows the arrangement of the magnets.

The floating magnet was placed near to the north pole of the fixed magnet. The floating magnet then moved along the path shown in Figure 6. Explain why.

The student replaced the floating magnet with a piece of iron. What happened to the piece of iron?

Describe how to use a compass to plot the magnetic field pattern around a bar magnet. Use Figure 7 to help you.

Figure 8 shows a diagram of an electromagnetic lock used to secure a door.

Figure 9 shows an incomplete sequence of how the door unlocks.

Write one letter in each box to show the correct sequence. A The iron bolt moves. B A magnetic field is created around the solenoid. C There is a current in the circuit.

The electromagnetic lock contains a spring. When the door is unlocked the extension of the spring is 0.040 m. spring constant = 200 N/m Calculate the elastic potential energy of the spring when the door is unlocked. Use the equation: elastic potential energy = 0.5 spring constant (extension)²

A door is fitted with a security lens and a lock. The security lens allows a person to see a visitor before opening the door. The security lens is concave.

Figure 5 is an incomplete ray diagram representing a visitor standing near the security lens. Complete Figure 5 to show how an image of the visitor is formed by the concave lens. Draw an arrow to represent the image.

The visitor moves further away from the security lens in the door. How does the size of the image change? Tick (✓) one box.

Figure 6 shows a diagram of the lock. The door unlocks when the switch is closed.

Which material should the bolt be made from? Tick (✓) one box.

Explain why the door unlocks when the switch is closed.

When the door unlocks, a force of 2.88 N is applied to the spring. The spring extends by 1.50 cm. Calculate the spring constant of the spring.

Give two ways the resultant force on the bolt could be increased.

Figure 5 shows a bar magnet. Each circle represents a compass.

Figure 5

Draw an arrow inside each circle to show the direction that each compass would point.

Figure 6 shows part of a coat. The coat has two magnets hidden inside the material. Figure 7 shows how the magnets are used to fasten the coat.

Explain why the magnets inside the coat must not have two south poles facing each other.

A coil of wire is connected to a battery. The current in the coil produces a magnetic field.

Which diagram in Figure 8 shows the magnetic field produced by the current in the coil?

Tick (✓) one box.

Figure 8

A solid rod is placed inside the coil. Which type of rod would make the magnetic field of the coil stronger?

Tick (✓) one box.

A student investigated how the strength of an electromagnet varies with the current in the coil of the electromagnet. Figure 9 shows the equipment the student used.

Figure 9

Why does the spring get longer when the electromagnet is switched on?

The student measured how much further the spring extended with different values of current in the coil. Figure 10 shows the results.

The current in the coil is increased from 0.6 A to 1.2 A Determine the increase in the extension of the spring.

Calculate the increase in the force on the spring when the current in the coil increased from 0.6 A to 1.2 A Spring constant = 0.18 N/cm Use the equation: force = spring constant × extension

Describe what happened to the strength of the electromagnet as the current in the coil increased from 1.2 A to 1.6 A

Figure 19 shows the back of a lorry. The lorry is used to carry horses.

The ramp is lowered by pulling on the rope or by pulling on the handle. The hinge acts as a pivot.

Explain why it is easier to lower the ramp by pulling on the rope rather than pulling on the handle.

When the ramp is lowered, work is done to stretch a spring on the side of the ramp. Elastic potential energy is stored in the stretched spring. Figure 20 shows the ramp part way down in a balanced horizontal position.

With the ramp horizontal: the moment caused by the weight of the ramp = 924 Nm the spring is stretched by 0.250 m

Calculate the elastic potential energy stored in the stretched spring. Use data from Figure 20.

A student carried out an investigation to determine the spring constant of a spring. Table 4 gives the data obtained by the student.

Describe a method the student could have used to obtain the data given in Table 4. Your answer should include any cause of inaccuracy in the data. Your answer may include a labelled diagram.

The student measured the extension for five different forces rather than just measuring the extension for one force. Suggest why.

Figure 15 shows some of the data obtained by the student.

Figure 15

Complete Figure 15 by plotting the missing data from Table 4. Draw the line of best fit. Table 4 is repeated here to help you answer this question.

Write down the equation that links extension, force and spring constant.

Calculate the spring constant of the spring that the student used. Give your answer in newtons per metre.

Hooke’s Law states that: ‘The extension of an elastic object is directly proportional to the force applied, provided the limit of proportionality is not exceeded.’ The student concluded that over the range of force used, the spring obeyed Hooke’s Law. Explain how the data supports the student’s conclusion.

A student carried out an investigation to determine the spring constant of a spring. Table 1 gives the data obtained by the student.

Describe a method the student could have used to obtain the data given in Table 1. Your answer should include any cause of inaccuracy in the data. Your answer may include a labelled diagram.

The student measured the extension for five different forces rather than just measuring the extension for one force. Suggest why.

Figure 2 shows some of the data obtained by the student.

Complete Figure 2 by plotting the missing data from Table 1. Draw the line of best fit. Table 1 is repeated here to help you answer this question.

Write down the equation that links extension, force and spring constant.

Calculate the spring constant of the spring that the student used. Give your answer in newtons per metre.

Hooke’s Law states that: ‘The extension of an elastic object is directly proportional to the force applied, provided the limit of proportionality is not exceeded.’ The student concluded that over the range of force used, the spring obeyed Hooke’s Law. Explain how the data supports the student’s conclusion.