How do you calculate the energies of particles going near the speed of light? It’s a little tricky, but you can do it if you have the right equation. Since the kinetic energy equation comes from Newton’s Laws of Motion, which don’t apply to particles moving near the speed of light, we have to add a correction factor from Einstein’s Theory of Relativity in order to compensate and make the equations accurate. Here’s the equation for particles going close to light speed:
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Remember that math gives us a way to describe what was written in the word problem.
As the boulder rolls down the hill, friction performs work against the boulder. That works takes away some of the energy. That’s how we arrive at KE = PE – WFS.
In this unit we learn about conservation of energy. The concept of potential energy equaling kinetic energy is a way to write out that concept as a formula.
As the car rolls up the emergency ramp, its kinetic energy (motion) is converted into potential energy. Once the car is at rest at the top of the ramp, it has only potential energy.
By using the PE and KE formulas together, we’re able to determine the distance it takes for the car to come to a stop.
In question 19, it uses the formula, ‘KE=PE-Wf’. Shouldn’t it be, ‘KE=PE+Wf’?
In question 13, it says that potential energy equals kinetic energy without any explanation. Why are they equal?