Kater's pendulum
Okay, so imagine you have a very special pendulum made out of a long rod and a weight at the end. This pendulum is so special because it helps us measure something called gravity.
When we hang the pendulum still, like this, we can start it swinging back and forth. As it swings, it moves back and forth in a straight line. This back-and-forth movement is called oscillation.
Now, let's say we hang the pendulum in a place where gravity is the same all around it - like in space. If we pull the weight at the end of the pendulum to one side and let go, it will swing back and forth in the same way every time, no matter how far we pull it.
But what if we hung the pendulum on Earth, where gravity is stronger closer to the ground? When we pull the weight back and let go, the pendulum will still swing back and forth, but it will move in a curve instead of a straight line. This is because the weight is being pulled down more strongly as it gets closer to the ground, and less strongly when it is higher up. The curve it moves in is called an ellipse.
Now, if we make the pendulum rod out of two different metals, one on top and one on bottom, they will expand and contract differently when they get hot or cold. This means the length of the rod will change slightly, making the pendulum swing a little faster or slower.
This is where Kater's Pendulum comes in. It was invented by a man named Captain Henry Kater in 1817 as a way to measure the strength of gravity more accurately. By adjusting the length of one of the rod pieces, Kater was able to find the perfect length that made the pendulum swing back and forth in a straight line, no matter what the temperature was.
So, by measuring the time it takes for the pendulum to swing back and forth in a straight line, we can use Kater's Pendulum to find out the strength of gravity at that specific location on Earth.
When we hang the pendulum still, like this, we can start it swinging back and forth. As it swings, it moves back and forth in a straight line. This back-and-forth movement is called oscillation.
Now, let's say we hang the pendulum in a place where gravity is the same all around it - like in space. If we pull the weight at the end of the pendulum to one side and let go, it will swing back and forth in the same way every time, no matter how far we pull it.
But what if we hung the pendulum on Earth, where gravity is stronger closer to the ground? When we pull the weight back and let go, the pendulum will still swing back and forth, but it will move in a curve instead of a straight line. This is because the weight is being pulled down more strongly as it gets closer to the ground, and less strongly when it is higher up. The curve it moves in is called an ellipse.
Now, if we make the pendulum rod out of two different metals, one on top and one on bottom, they will expand and contract differently when they get hot or cold. This means the length of the rod will change slightly, making the pendulum swing a little faster or slower.
This is where Kater's Pendulum comes in. It was invented by a man named Captain Henry Kater in 1817 as a way to measure the strength of gravity more accurately. By adjusting the length of one of the rod pieces, Kater was able to find the perfect length that made the pendulum swing back and forth in a straight line, no matter what the temperature was.
So, by measuring the time it takes for the pendulum to swing back and forth in a straight line, we can use Kater's Pendulum to find out the strength of gravity at that specific location on Earth.