Intro to Conservation of Energy Video Lessons

Concept

# Problem: A 30 N ball and a 80 N ball are dropped at the same time from a height of 10 meters. Air resistance is negligible. Which of the following statements is accurate?a) Both balls hit the ground at the same time but gravity does more work on the heavy ball than on the light ball.b) The heavy ball has a greater acceleration and falls faster.c) The light ball has a greater speed since it can accelerate faster than the heavy ball.d) After 1 second has elapsed, both balls have the same kinetic energy since they have the same acceleration.

###### FREE Expert Solution

In this problem, we're going to apply the conservation of energy.

$\overline{){\mathbf{m}}{\mathbf{g}}{\mathbf{h}}{\mathbf{=}}\frac{\mathbf{1}}{\mathbf{2}}{\mathbf{m}}{{\mathbf{v}}}^{{\mathbf{2}}}}$

We can then solve for v as:

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###### Problem Details

A 30 N ball and a 80 N ball are dropped at the same time from a height of 10 meters. Air resistance is negligible. Which of the following statements is accurate?

a) Both balls hit the ground at the same time but gravity does more work on the heavy ball than on the light ball.

b) The heavy ball has a greater acceleration and falls faster.

c) The light ball has a greater speed since it can accelerate faster than the heavy ball.

d) After 1 second has elapsed, both balls have the same kinetic energy since they have the same acceleration.