Questions about simple pendulum

[buffgilville]

1) A simple pendulum consist of a mass m tied to a string (considered massless) of length L. So would a baseball bat suspended from one end, swinging back and forth, make a simple pendulum?

No, right? because the "string" in this case is not massless. Does the string that is swinging the mass always have to be massless for it to be a simple pendulum?

2) Under what conditions does an oscillating mass tied to a string constitute a simple pendulum?

Is it considered a simple pendulum when the mass is displaced from the suspension point?

3) The period of the variable-g pendulum is T^2 = K(1/geff).
Upon what variables does K depend? (Hint: The moment of inertia is involved.)

don't know about this question

 

[Doc Al]

These questions strike me as a bit odd.

1) A simple pendulum consist of a mass m tied to a string (considered massless) of length L. So would a baseball bat suspended from one end, swinging back and forth, make a simple pendulum?

No, right? because the "string" in this case is not massless. Does the string that is swinging the mass always have to be massless for it to be a simple pendulum?

By usual definition, a simple pendulum is a point mass at the end of a massless "string". So, right, a baseball bat is not a "simple pendulum", but would be an example of a physical pendulum. But I'm not getting the point of the question.

2) Under what conditions does an oscillating mass tied to a string constitute a simple pendulum?

Is it considered a simple pendulum when the mass is displaced from the suspension point?

Again, I have a hard time understanding the question. What's an "oscillating mass"? Do they mean a mass swinging at the end of a string? If the string is massless, it's a simple pendulum.

I'm guessing that they are looking for is under what conditions does this pendulum exhibit simple harmonic motion. Try answering that one.

3) The period of the variable-g pendulum is T^2 = K(1/geff).
Upon what variables does K depend? (Hint: The moment of inertia is involved.)

I don't know what a "variable-g" pendulum is. In any case, figure out (or look up) the equation for the period of a physical pendulum.

 

[wais]

1) No, a baseball bat suspended from one end would not make a simple pendulum because the string is not considered massless. The definition of a simple pendulum includes a mass tied to a massless string, so the baseball bat would not meet this requirement.

2) An oscillating mass tied to a massless string constitutes a simple pendulum when the amplitude of the swing is small, the mass is concentrated at a single point, and the string is considered massless.

3) The variable-g pendulum equation, T^2 = K(1/geff), depends on several variables such as the length of the pendulum, the mass of the object, and the acceleration due to gravity. The value of K in the equation also depends on the moment of inertia of the pendulum, which is a measure of the object's resistance to rotational motion. Therefore, the variables that K depends on are the length, mass, acceleration due to gravity, and moment of inertia of the pendulum.