So let us look at this example, what I've drawn here is a roller coaster, so the blue line is the
path that the roller coaster will follow from a high point at 20 meters at point A to a lower point
at point B.
Initially at point, the roller coaster is stationary, doesn't move, so it has zero kinetic energy,
but because it is at a height of 20 meters, it has a potential energy that we can calculate because
we know the mass of this roller coaster cord is 300 kilograms.
Now, the question is, what is the velocity of this roller coaster when it reaches point B, we can
ignore friction and we can ignore the air resistance.
So let us investigate this court in terms of its energy at point and at point B, so at point A. the
question stated that the court is stationary.
So we know that the kinetic energy, the first position will be zero.
But it is at a height of 20 meters relative to point B, so we can calculate a potential energy which
is equal to engage, which is equal to 300 multiplied by nine point eight, one multiplied by twenty,
which gives us thirty eight thousand eight hundred and sixty joules.
That's the same unit for energy.
At point B.
It has now reached.
A zero distance from the reference line, so the potential energy will be zero, but it will have a
certain velocity.
So there will be a kinetic energy and that kinetic energy is calculated by one half in the square.
Now, we don't know what is V that is what we want to calculate.
So let us write down the principle of energy conservation, kinetic energy one plus potential energy.
One is kinetic energy two plus potential energy to.
So zero, this is a point a plus.
Fifty eight thousand eight hundred and sixty is equal to one half in the squared plus zero.
That would be at point B because we know the mass.
We can substitute that for him and we can solve for the velocity at point B to be nineteen point eight
meters per second.
This is a fairly simple example, but it illustrates the principle and the principle is that the total
amount of energy in the system stays the same, but it is exchanged between different forms.
It is exchanged between kinetic energy and potential energy.
And so at point A. we knew what was the total amount of energy because it was only potential energy.
And at point B, we knew the potential energy is zero.
So that energy at point B was the kinetic energy and therefore we could solve for the velocity of.