Write the kinetic, potential and total energy of a baseball having a mass of 0.145kg held 10 meters above the ground.

Question

1. Write the kinetic, potential and total energy of a baseball having a mass of 0.145kg held 10 meters above the ground.
2. The baseball was released under the influence of gravity on Earth and freefalls to the ground. Write the kinetic, potential and total energy of the baseball at the point the baseball hits the earth.
3. What is the baseball’s final speed when it impacts the ground using the principles of Energy Conservation?

Answer 1

1) Since the ball is initially at rest, the initial kinetic energy is 0. We can use the equation E_p=mgh to find it's gravitational potential energy, or 0.145kg * 9.81m/s² * 10m = 14.2245 kg*(m/s)². These are the units for Joules.

2) After falling the 10 meters, all of that energy is converted to kinetic energy. The numbers are simply flipped.

3) Since all of the energy is kinetic, we can use E_k = 1/2 mv². By re-arranging we see that v = (2E_k/m)^1/2. Plugging in the numbers, the final answer is (2*14.2245J / 0.145m)^1/2 = 14.007141 m/s.

If you typed the question in correctly, the question only gives 1 significant figure (10 m), so all answers need to be rounded to 1 sig fig likewise.