What Are the True Statements About Tension in a Simple Pendulum?

[lmlgrey]

Simple pendulum question.. help needed!

http://capa.mcgill.ca/res/mcgill/dcmcgill/oldproblems/msuphysislib/Graphics/Gtype26/prob34a_pendSHM1.gif1.[/URL] The diagram shows a simple pendulum consisting of a mass M suspended by a thin string. The magnitude of the tension is T. The mass swings back and forth between ±q0 Choose True or False

True False T is greater than Mg for q = q0.
True False T equals Mg when q = q0.
True False T=Mg at some angle between zero and q0.
True False The vertical component of tension is constant.









2. is it true that T = mg*cos(theta) always?



The vertical component of tension is constant ... true, since the vertical component=force of gravity
T is greater than mg when q=q0. ... false, since q0 is the apex, and T is the smallest when the ampliude is the greatest

I don't know about the other two...especially: T=Mg at some angle between zero and q0
my guess at that question is that since T= Mgcos(theta), therefore, T will only equal to mg when theta=0 or 180? so it would be false?

 

[tiny-tim]

The diagram shows a simple pendulum consisting of a mass M suspended by a thin string. The magnitude of the tension is T. The mass swings back and forth between ±q0

Hi lmlgrey!

Don't guess!

Physics is equations, so always find the right equation, and follow it through.

In this case, the right equation is Newton's second law, F = ma.

Most of your answer is wrong, because you've ignored the ma part.

Try again!