Practice Paper 2 (SL IB Physics)

Water at constant pressure boils at a constant temperature.

Outline the reason for this, in terms of the energy of the molecules.

In an experiment to measure the specific latent heat of vaporization of water, steam at 100°C was passed into water in an insulated container.

The following data are available.

• Initial mass of water in container = 0.260 kg
• Final mass of water in container = 0.278 kg
• Initial temperature of water in container = 20.4 °C
• Final temperature of water in container = 53.4 °C
• Specific heat capacity of water = 4.18 × 10³ J kg^–1 K^–1

Show that the specific latent heat of vaporization of water is about 1.8 × 10⁶ J kg^–1.

The diagram shows a battery of e.m.f. 40.0 V and internal resistance, r.

The current in the battery is 2.5 A. 

Calculate the internal resistance r.

Calculate the energy dissipated in the battery in 3.5 minutes.

The circuit is amended to include a solar cell. 

Explain the function of a solar cell and an advantage it has in an electric circuit over a chemical cell.

The internal resistance of the cell affects the efficiency of the transfer of energy from the cell to the circuit. 

Explain what causes internal resistance and why this affects the efficiency of the cell.

The diagram shows a stationary wave source, R, in water. The source produces waves with a constant frequency. The distance between each successive wavefront is equal to the wavelength of the waves produced by R.

The speed of the waves in water is v.

Sketch three successive wavefronts produced when the source is moving to the right at a speed of 0.75v. 

A scientist sits on a boat to the right of the source and measures the frequency of the waves as they approach.

Explain the observations the scientist will make.

Four point charges A, B, C and D are each placed at a distance d from O as shown below.

A has a charge –q and B, C and D each have a charge +q­.

Write an expression for the magnitude of the resultant electric field strength at O in terms of q and d.

The arrangement of the charges is changed to the grid shown below. Each charge is now the corner of a square of side x, where x = 2d.

Write an expression for the magnitude of the resultant electric field strength at point O in terms of q and d.

An alpha particle with an initial speed one-tenth that of the speed of light is fired head-on at a stationary gold nucleus .

Calculate the minimum separation between the alpha particle and the centre of the gold nucleus.

When scientists develop climate models for planets other than Earth, the value of the solar constant  must be adjusted.

Explain why is a constant and how it can be adjusted for different planets in the Solar System.

Different climate models consider the energy absorbed by the Earth with and without an atmosphere.

Explain why the average power absorbed per unit area of the Earth is less than in both models.

A simplified energy balance model of the Earth with an atmosphere is shown in the diagram.

In this model, the Earth's surface is assumed to be a black body radiator at constant temperature . It receives both solar radiation and radiation emitted from the atmosphere. The atmosphere is modelled as a body with albedo and average equilibrium temperature .

Determine the value of  used in this model.

Calculate the average equilibrium temperature of the Earth's surface . 

Compare and contrast the roles of carbon dioxide and water vapour in the greenhouse effect. 

Suggest why the burning of fossil fuels may lead to an increase in global warming by the enhanced greenhouse effect.