8 Four students P, Q, R and S each attempt to measure the time period (the time for one complete 090ilation) of a pendulum. The arrows in Fig. 21 show the movements of the pendulum that each
student times
P
end
(1)
Ind
(a) State the student who has chosen the correct movement for one period of a pendulum
student​

Idk just need points

Yup your right can give me more detail  

D; ) ; ) ; ) ; ) ; ) ok enough but fr  short answer

The answer is  the gravitational potential energy it had from being above the ground is converted to kinetic energy as the rock falls. as kinetic energy increases, the velocity of the rock will also increase. however, if one considers the air, the rock will lose energy as it falls due to air resistance. if the cliff is high enough, the acceleration due to gravity and the air resistance due to the velocity will be exactly equal and there will be no change in kinetic energy.  hope its and mostly important have a nice day ; )