Exam Questions Flashcards
State the name given to satellites that orbit the earth, with a period of 1 day, above the equator
Geostationary satellites
Name an advantage of using geostationary satellites
Dish can be fixed to point in one direction
State Kepler’s third law
The cube of the planets distance from the sun divided by the square of the orbital radius is the same for all planets
State the term used for the energy required to change a solid into a liquid
Specific latent heat OF FUSION
Explain, in terms of the behaviour of molecules, how a gas exerts a pressure on the walls of its container
Molecules collide with the walls
Change in momentum occurs when molecules collide with walls
Force = rate of change of momentum
Pressure = total force/area
Molar mass of hydrogen gas is 2.02 x 10^-3 kg/mol. Calculate the mass of a hydrogen molecule
Divide by Avogadro constant
= 3.4 x 10^-27
State the maximum range in air for alpha and beta radiation
Alpha - 0.04 m
Beta - 0.4 m
γ rays have a range of at least 1 km in air.
However, a γ ray detector placed 0.5 m from a γ ray source detects a noticeably smaller count-rate as it is moved a few centimetres further away from the source.
Explain this observation.
Inverse square law of gamma radiation
Positive kaons have unusually long lifetimes.
Give a reason why you would expect this to be the case.
They have strangeness
A friend who has not studied physics suggests that a smoke detector containing radioactive material should not be sold.
Use your knowledge of physics to explain why a smoke detector containing americium-241 does not provide any risk to the user.
Alpha has a short range
Only a small quantity emitted
