Define root mean square speed
square root of the mean of the squares of individual particles in a gas
State the difference between systemic and random error
random errors cause unpredictable variation in repeated measurements and reduced precision, whereas systematic errors shift all results in the direction and reduces accuracy
Explain why the pressure of a gas increases when temperature increases, assuming volume is constant. (3)
Increasing temperature increases average kinetic energy of gas
Molecules move faster
Collide with container walls more frequently and with greater momentum change
Increases force on walls, so pressure increases
Explain what is meant by the following term: free vibration (1)
no energy transferred to or from system
Explain what is meant by the following term: forced vibration (1)
forced to oscillate at frequency of an external oscillator giving it energy
The ITER fusion reactor has been designed to produced the required conditions for fusion to take place. Outline the basic principles of its operation. (3)
Charged plasma particles
Circulate in helical paths
Produced by field coils
Transfer heating action
Explain why it is difficult to achieve fusion in the ITER fusion reactor. (2)
Difficult to achieve high temperatures
for sufficient time
From the table the specific heat capacity of water at room temperature is 4.2x10 3 Jkg-1K-1. Explain what is meant by this statement. (1)
4.2x10 3 J of thermal energy required to increase the temperature of 1kg of water by 1oC
The specific heat capacity of water is large compared to most other substances. Using this fact explain why water is used as a coolant in a car radiator. (1)
A small temperature rise occurs for a given heat input
Define simple harmonic motion
Acceleration (directly) proportional to displacement/distance from fixed point and directed towards that point
Explain why the microscope is movable in Rutherford’s scattering experiment. (1)
detect alpha particles at all angles/scattered
Explain what is meant by the mass defect of an atomic nucleus (1)
Difference between the mass of separated nucleons and the combined mass of the nucleus
Sketch the shape of the graph of binding energy per nucleon against mass number and indicate the approximate position of iron-56 on the graph. Explain the relationship between the position of the nucleus on the curve and the stability of the nucleus. (2)
Correct curve with Fe near peak [1]
Nuclides with higher BE/nucleon most stable (as takes more energy to disintegrate) [1]
Explain why plasma confinement and high particle kinetic energy are required for nuclear fusion to take place. (2)
extremely high energies needed to overcome electrostatic repulsion/increasing chances of collision/maintains high temperature
Briefly describe three methods of plasma confinement in nuclear fusion. (4)
Gravitational – extremely large mass uses gravity
Inertial – fuel pellets bombarded with laser energy shock wave creates pressure and heat in core
Magnetic – magnetic bottle plasma held with magnetic field
