A student investigates whether the Stefan-Boltzmann law, , applies to stars.
L= luminosity of the star, in W
Stefan-Boltzmann constant
R= radius of the star, in m
T= surface temperature of the star, in K
To verify the law, they obtain values from databases and manipulate the data as shown.
Outline a conclusion for the investigation.
A student studies the relationship between the centripetal force applied to an object undergoing circular motion and its period T.
The object (mass m ) is attached by a light inextensible string, through a tube, to a weight W which hangs vertically. The string is free to move through the tube. A student swings the mass in a horizontal, circular path, adjusting the period T of the motion until the radius r is constant. The radius of the circle and the mass of the object are measured and remain constant for the entire experiment.
The student collects the measurements of T five times, for weight W. The weight is then doubled ( 2 W ) and the data collection repeated. Then it is repeated with 3 W and 4 W. The results are expected to support the relationship
The measurements of T were collected five times. Explain how repeated measurements of T reduced the random error in the final experimental value of m r.
Outline why repeated measurements of T would not reduce any systematic error in T. provided.
A satellite powered by solar cells directed towards the Sun is in a polar orbit about the Earth.
The satellite is orbiting the Earth at a distance of 6600 km from the centre of the Earth.
Not all scientists agree that global warming is caused by the activities of man. Outline how scientists try to ensure agreement on a scientific issue.