Energy is released in some power stations and in the Sun by either nuclear fission or nuclear fusion. Which type of nuclear reaction applies in each case?

A school keeps radioactive sources for use in radioactivity experiments in a laboratory. The background radiation is …

Which nuclides have the same number of neutrons in a nucleus?

Where is energy released by the fusion of hydrogen nuclei to form helium?

The table shows the weights and masses of four objects on different planets. On which planet is the gravitational fie…

Four forces act at a point as shown. What is the size of the resultant force?

A student drops, from rest, a table-tennis ball in air. What happens to the velocity and to the acceleration of the b…