Just before your mountain bike ride, you eat a 240 Calorie exercise bar. (You can find the conversion between food Calories and Joules in the People’s Physics chapter and several references online.) The carbon bonds in the food are broken down in your stomach, releasing energy. About half of this energy is lost due to inefficiencies in your digestive system.
Given the losses in your digestive system how much of the energy, in Joules, can you use from the exercise bar? __________________________
After eating, you climb a 500 m hill on your bike. The combined mass of you and your bike is 75 kg.
How much gravitational potential energy has been gained by you and your bike? __________________________________________________________
Where did this energy come from? ______________________________________
If you ride quickly down the mountain without braking but losing half the energy to air resistance, how fast are you going when you get to the bottom? _________________
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yes
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