Consider the energy we use everyday in routine tasks, where that energy comes from, and where it goes. When you climb stairs you overcome the force of gravity to raise yourself to some height. It does not matter what the slope of the stairs are; the work done is against gravity which is always vertical so only the height counts. Take a typical human mass of 65 kg (roughly 143 lb of gravitational pull or weight) and a stairway up 2 stories which is about 6 meters. If you drop a coin from the top of the stairs down to the bottom of the stairwell, what is the velocity of the coin when it reaches the floor? After you walk back down the stairs to retrieve your coin, how much work did you do to descend?
Consider the energy we use everyday in routine tasks, where that energy comes from, and where it goes. When you climb stairs you overcome the force of gravity to raise yourself to some height. It does not matter what the slope of the stairs are; the work done is against gravity which is always vertical so only the height counts. Take a typical human mass of 65 kg (roughly 143 lb of gravitational pull or weight) and a stairway up 2 stories which is about 6 meters.
- If you drop a coin from the top of the stairs down to the bottom of the stairwell, what is the velocity of the coin when it reaches the floor?
- After you walk back down the stairs to retrieve your coin, how much work did you do to descend?
Subpart (1):
According to the conservation of energy, the total energy of any system is always conserved.
The amount of energy that is stored within the coin when the person reaches the top of the stairway is equal to the amount of potential energy stored by the person and so is true for the coin.
When the coin reaches the floor, the potential energy is totally converted in the kinetic energy of the coin.
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