A student wants to verify the relation between the period T of a simple pendulum and the length L of the pendulum, where g is the acceleration of free fall. The student operates a stopwatch to measure one oscillation and a millimeter ruler to measure the length of the pendulum.
State, for this experiment,
one variable that must be controlled,
A group of students uses pressurized air to move a piston that forces a nail into a block of wood. A gauge is used to measure the pressure P of compressed air above atmospheric pressure. The nail enters the wood perpendicular to its surface.
The students use a ruler to measure the length of the nail which remains above the surface of the wood as shown. The depth of the nail inside the wood is d. All necessary length measurements are recorded using a ruler with uncertainty .
The students systematically increase the pressure and calculate d.
State one variable that needs to be controlled when collecting the data.
A student performs an experiment with a rod that is free to oscillate in a horizontal plane. Two identical small spheres, each of mass m, are placed at equal distances from the centre of the rod. The student records values of the period of oscillation of the rod T in seconds for different values of the distance of separation of the spheres d, in metres.
The student plots the variation with d of T, keeping m constant.
Explain why m was kept constant.
State one other feature of the experiment that the student should keep constant.