Solve Pendulum Problem: Length .76m, Mass .365kg, Angle 12˚

[vinny380]

The length of a simple pendulum is .760m, the pendulum bob has a mass of .365 kg, and it is released at at angle 12 degress to the vertical.
A. Find the frequency. Assume SHM.
B. What is the pendulum bob's speed when it passes through the lowest point of the swing
C. What is the tot al energy stored in this oscilation, assuming no loses.

So A is really easy:
F=(1/2pi)sqrt(9.8/.76)
F= .57

For me, B is the hardest part because I can not find a relevant formula connecting velocity with pendulums. Can anyone advise me how to do this part??

C. I haven't worked on this part yet, but I am ready sure you just have to use the formula E= .5mv^2 +.5kx^2.

Thanks!

 

[Doc Al]

For me, B is the hardest part because I can not find a relevant formula connecting velocity with pendulums. Can anyone advise me how to do this part??

Consider conservation of mechanical energy.

C. I haven't worked on this part yet, but I am ready sure you just have to use the formula E= .5mv^2 +.5kx^2.

That last term is elastic potential energy--but I don't see any springs in this problem. What other form of energy is relevant here?

 

[radou]

Hint regarding B: conservation of energy.

Edit: too late.

 

[vinny380]

so I should use this for B : (1/2)mv2 + (1/2)Iω2 ??

 

[Doc Al]

No. What two types of mechanical energy are involved as the pendulum swings?

 

[vinny380]

Potential and Kinetic energy?

 

[Doc Al]

Yes, but what kind of potential energy?

 

[vinny380]

mechanical potential energy ?

 

[Doc Al]

Here's a hint: What kind of energy changes as the bob rises and falls?

 

[crcrzy12]

potential and Kinetic

 

[dkoppes]

Gravitational potential