Any1 gud in physics??? help me pls!!!?

Question

(a) Investigate whether a simple pendulum will swing continuously in air.Explain your findings.Suggest the conditions required for a pendulum to swing continuously.

(b) If a pendulum is made to swing in water, compare the time taken for this pendulum to come to a complete stop with the time taken by a pendulum swinging in air.Explain the difference.

Answer 1

From my knowledge (Only have grade 11 physics knowledge)

A)In our world a pendulum would not swing continously in the air without a motor or some short. This is because of friction and other facters which convert the potential energy in the Pendulum into other forms, ie. sound, heat, etc. (on a pendulum this would be produced in small amounts due to lower friction.)

The conditions needed for a continuous swing (won't stop) you need a friction less world and you also need a place where no other forces  will act upon the pendulum. Refer to Newtons first and second law.

B) If you made a pendulum to swing in water and it was again a simple design, no motors, etc. The one in the water would stop MUCH sooner then the one in the air. This difference is caused due to more friction occuring in the water.

There are probably other reasons for this as well just I'm on summer break so I forgot most of them lol. Just think of it this way, More Friction = More Energy Required to move the object.