Activity 3: Review mechanical energy
Investigate kinetic and potential energy (mechanical energy) by solving some mathematical problems of real life examples. The level of difficulty of problems related to mechanical energy is straight forward because of the characteristics of parameters that are involved in the formula. Electrical energy and thermal energy for example are introduced in university level physics course in further details, but solving mechanical energy problems are simple enough for students in Grade 12. Teachers can emphasize how convenient and economic the formula are.
Ex. A diver, of mass 57.8 kg, climbs up a diving-board ladder and then walks to the edge of the board. He then steps off the board and falls vertically from rest to the water 3.00 m below. Draw a diagram that explains the situation and determine the diver's gravitational potential energy at the edge of the diving board, relative to the water (Hirsch, 2003).
Solution: m=57.8 kg; g=9.80 m/s^2; y=3.00 m;
Energy = mgy = (57.8 kg)(9.80 m/s^2)(3.00 m) = 1.70 X 10^3 J
Ex. A diver, of mass 57.8 kg, climbs up a diving-board ladder and then walks to the edge of the board. He then steps off the board and falls vertically from rest to the water 3.00 m below. Draw a diagram that explains the situation and determine the diver's gravitational potential energy at the edge of the diving board, relative to the water (Hirsch, 2003).
Solution: m=57.8 kg; g=9.80 m/s^2; y=3.00 m;
Energy = mgy = (57.8 kg)(9.80 m/s^2)(3.00 m) = 1.70 X 10^3 J