Water at the base of a waterfall has a higher temperature than water at the top. Energy from the water’s gravitational potential store at the top is transferred into the thermal store at the bottom. The specific heat capacity of water is $4200\ \text{J kg}^{-1}\,^{\circ}\text{C}^{-1}$. What temperature difference does a waterfall of height $21\ \text{m}$ produce?
- A$0.0050\ ^{\circ}\text{C}$
- B$0.049\ ^{\circ}\text{C}$
- C$20\ ^{\circ}\text{C}$
- D$200\ ^{\circ}\text{C}$