The Physics of Sandcastles and Ladders

We invite any aspiring physicists to try their hand at these physics problems dealing with light, atoms and force: Estimate the number of visible photons leaving a 60W light bulb per second. How big would a sandcastle be if you made it from the same number of grains of sand as there are atoms in…

Momentum and Energy

We invite any aspiring physicists to try their hand at these physics problems dealing with the concepts of momentum and energy: Martial arts such as Judo, Aikido and Japanese Jiu Jitsu teach dynamic throws. These are explained to students as redirecting their attacker’s momentum. Can you explain this by separately considering the linear motion of…

Human powered helicopter

Try your hand at some physics problems based on gravity set by St John’s Physics tutor Professor Tony Weidberg… Q: Many proposals have been made for a human powered helicopter. Consider the case of such a machine with a rotor 10 metres in diameter. Could a human create enough power to overcome gravity? The density…

Heating and cooling

Try your hand at some physics problems based on heating and cooling set by St John’s Physics tutor Professor Tony Weidberg… Q: You want to heat a cold room using a simple electric bar heater. This consists of one conducting wire connected to the mains via a plug. In order to maximise the power, should you…

The physics of making a cup of tea

St John’s Physics Tutor Professor Tony Weidberg loves a good cup of tea, so why not make yourself a brew and have a go at his physics brainteasers… Q: At the interval during a football world cup game, some people watching at home make a cup of tea using electric kettles. Make a reasoned order of…

Physics Brainteasers

Try your hand at some fun Physics brainteasers set by St John’s Physics Tutor Professor Tony Weidberg… Q: Explain how many high tides would be observed per day at a given point on the Earth. Q: In a popular science article on nuclear fusion it was claimed that two parallel electron beams could attract each…