# Physics

posted by .

Two physical pendulums (not simple pendulums) are made from meter sticks that are suspended from the ceiling at one end. The sticks are uniform and are identical in all respects, except that one is made of wood (mass=0.34 kg) and the other of metal (mass=0.63 kg) They are set into oscillation and execute simple harmonic motion. Determine the period of (a) the wood pendulum and (b) the metal pendulum

We know that

omega = 2*pi*freq = sqrt(mgL/I), where m is the mass, g is the acceleration due to gravity, and I is the moment of inertia.

So, if we can evaluate the equation above, we can get the frequency, and then take 1/freq in order to get the period.

However, don't we need the moment of Intertia, I, for the meter stick?

How do we solve this?

Thanks!

• Physics -

They are both meter sticks. Note that M/I appears in the frequency equation. I is proportional to M so Mass cancels out.

They will both have the same period.

If they swing from one end, I = M L^2/3

M/I = L^2/3

• Physics -

Maybe I don't understand..

If I=m (L^2) /3, then we have:

w=2 pi f = sqrt(mgL/I)

Subbing in I, we have:

2 pi f = sqrt(g L / (L^2/3) )

=sqrt(3g/L)

Thus, we have:

f=1/(2pi) * sqrt(3*g/L)=1/(2pi) * sqrt(3*9.8/1) = 0.862992.

This would mean that the period should be:

1/ freq = 1/0.862992, but I don't believe this answer is correct.

## Similar Questions

1. ### Physics

Hello, I posted this a bit ago, but am not sure the suggested solution was correct. Two physical pendulums (not simple pendulums) are made from meter sticks that are suspended from the ceiling at one end. The sticks are uniform and …
2. ### Physics

Two physical pendulums (not simple pendulums) are made from meter sticks that are suspended from the ceiling at one end. The sticks are uniform and are identical in all respects, except that one is made of wood (mass = 0.17 kg) and …
3. ### Physics

Two physical pendulums (not simple pendulums) are made from meter sticks that are suspended from the ceiling at one end. The sticks are uniform and are identical in all respects, except that one is made of wood (mass = 0.17 kg) and …
4. ### physics

Three identical uniform meter sticks are placed on the floor. The first stick lies along the y axis from y = 0.470 m to y = 1.47 m. The second stick lies along the x axis from x = 0.320 m to x = 1.32 m. The third stick is positioned …
5. ### Physics

Two pendulums are set up side by side. One pendulum P, consists of a 0.240 kg mass that is suspended on a string that is 65.0 cm long. The other pendulum, Q, has a 0.360 kg mass that is suspended on a string that is 39.0 cm long. The …
6. ### Physics

Two physical pendulums (not simple pendulums) are made from meter sticks that are suspended from the ceiling at one end. The sticks are uniform and are identical in all respects, except that one is made of wood (mass = 0.17 kg) and …
7. ### physics Classical Mechanics

a) Two pendulums consist of a very thin string at the end of which hangs a mass which is much larger than the mass of the rod. In pendulum #1, the rod is made of copper. In pendulum #2, the rod is made of invar. What is the percentage …
8. ### physics

Three identical uniform meter sticks are placed on the floor. The first stick lies along the y axis from y = 0.320 m to y = 1.32 m. The second stick lies along the x axis from x = 0.330 m to x = 1.33 m. The third stick is positioned …
9. ### Physics- Ballistic pendulum

A simple pendulum is made from a 2 kg. block of wood suspended from a light cord of length 1 m. When the pendulum is hanging in such a way that it is stationary and vertical, a bullet is shot horizontally into the block of wood where …
10. ### geometry

A triangle is made of wood sticks of lengths 8, 15 and 17 inches joined end-to-end. Pieces of the same integral length are cut from each of the sticks so that the three remaining pieces can no longer form a triangle. How many inches …

More Similar Questions