Does the weight of a pendulum's bob effect the time of the swing?

Question

Does a heavier bob make the swing of the pendulum swing faster or slower or not even change it?

Answer 1

The length of the string, and the strength of gravity, are the only variables that affects the period of the pendulum.

Assuming that you're not adjusting gravity ;-) the length is the only pertinent variable.

Answer 2

The weight of the bob will affect the period of the swing if the rod by which it is attached to the pivot point has a non-negligible moment of inertia. A more massive bob will then shift the center of gravity for the pendulum as a whole toward the bob. Whether this speeds up or slows down the pendulum depends on whether the changed mass shifts the center of gravity toward or away from the pivot. If the more massive bob shifts the center away from the pivot, the pendulum's swing will slow down.

Answer 3

No, and why should it? All things fall at the same rate, regardless of mass. If all things fall at the same rate, and gravity is what makes a pendulum swing, then by extension, all things swing at the same rate for a given length of string.

Mathematically, we can arrive at this conclusion from conservation of energy.

mgh=1/2*m*v^2

2gh=v^2

w=v/L, where w is the angular speed, which is measured in radians per second, and L is the length of the string.

v=wL

So

2gh=w^2*L^2

But h is the height of our object to begin with. If the string is rotated so that it's parallel with the ground, then h=L, since it's just the length of the string rotated.

So

2gL=w^2*L^2

w^2=2g/L

w=2*pi/T, where T is the period of the swing.

So

4*pi^2/T^2=2g/L

T^2=2*L*pi^2/g

T=sqrt(2*pi*L/g)

So you see, the time it takes to swing there and back is independent of the mass, m, but dependent on gravity and the length of the string.

So a pendulum will swing much faster if it's on Jupiter, or if you make the string really short.

Answer 4

Pendulum Weight

Answer 5

The LENGTH of the pendulum governs the swing time (Period) taken.

Answer 6

lol i dunno yet, i have to do that lab for my chemistry class, but i didnt finish it yet. but i was looking for wether the lenght of the string affects it instead of weight