$\mathbf{PE}\mathbf{}\mathbf{=}\mathbf{}\mathbf{m}\mathbf{\times}\mathbf{g}\mathbf{\times}\mathbf{h}\phantom{\rule{0ex}{0ex}}\mathbf{PE}\mathbf{}\mathbf{=}\mathbf{(}\mathbf{2}\mathbf{.}\mathbf{70}\mathbf{}\frac{\overline{)\mathbf{g}}}{\overline{){\mathbf{cm}}^{\mathbf{3}}}}\mathbf{\times}\mathbf{196}\mathbf{}\overline{){\mathbf{cm}}^{\mathbf{3}}}\mathbf{\times}\frac{\mathbf{1}\mathbf{}\mathbf{kg}}{{\mathbf{10}}^{\mathbf{3}}\mathbf{}\overline{)\mathbf{g}}}\mathbf{)}\mathbf{(}\mathbf{9}\mathbf{.}\mathbf{8}\mathbf{}\frac{\mathbf{m}}{{\mathbf{s}}^{\mathbf{2}}}\mathbf{)}\mathbf{(}\mathbf{2}\mathbf{.}\mathbf{1}\mathbf{}\mathbf{m}\mathbf{)}$

**PE = 10.89 J**

Consider the two spheres shown here, one made of silver and the other of aluminum. The spheres are dropped from a height of 2.1 m.

What is the kinetic energy of the silver sphere at the moment it hits the ground? (Assume that energy is conserved during the fall and that 100% of the sphere’s initial potential energy is converted to kinetic energy by the time impact occurs.)

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Kinetic & Potential Energy concept. You can view video lessons to learn Kinetic & Potential Energy. Or if you need more Kinetic & Potential Energy practice, you can also practice Kinetic & Potential Energy practice problems.