The above 3 formulas are used for solving problems involving energy calculations. If you know 2 of the 3 variables the third can be calculated.
As usual, here at www.1728.com, we have a calculator that will do all the work for you.

This ultra calculator is special by allowing you to choose among a great variety of units. Unlike other calculators, you are NOT confined to inputting mass in grams, velocity in meters per second, etc. making this calculator quite versatile.

1) What is the mass of a bullet traveling at 1,150 feet per second with an energy of 85.145 foot pounds?
The most important step in using this calculator is:
FIRST CHOOSE WHAT YOU ARE SOLVING FOR
In this case we are solving for MASS, so click on that button.
Enter 1,150 in the "velocity" box and choose feet per second from its menu.
Enter 85.145 in the "energy" box and choose foot pounds from its menu.
Click the CALCULATE button and you will see this equals 29 grains.
PLUS you get to see the answer in 7 other different units !!

2) A 4,000 pound car has an energy of 500,000 foot pounds.
What is its velocity?
FIRST CHOOSE WHAT YOU ARE SOLVING FOR
In this case we are solving for VELOCITY, so click on that button.
Enter 4,000 in the "mass" box and choose pounds from its menu.
Enter 500,000 in the "energy" box and choose foot pounds from its menu.
Click the CALCULATE button and this equals 61.149 miles per hour.
AND you get to see the answer in 7 other different units !!

3) A woman with a mass of 95 pounds is running at 10 miles per hour.
What is her kinetic energy?
FIRST CHOOSE WHAT YOU ARE SOLVING FOR
In this case we are solving for ENERGY, so click on that button.
Enter 95 in the "mass" box and choose pounds from its menu.
Enter 10 in the "velocity" box and choose miles per hour from its menu.
Click the CALCULATE button and you will see this equals 317.58 foot pounds.
AND you get to see the answer in 7 other different units !!

Here's hoping this calculator helps you with those physics problems.