You are hungry and decide to go to your favorite neighborhood fast-food restaurant. You leave your apartment and take the elevat
1 answer:
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Answer:
a) The change in potential energy of a 3.0 kilograms backpack carried up the stairs.
b) The change in potential energy of a persona with weight 650 newtons that descends the stairs is -2665 joules.
Explanation:
Let consider the bottom of the first floor in a building as the zero reference (). The change in potential energy experimented by a particle (
), measured in joules, is:
(1)
Where:
- Mass, measured in kilograms.
- Gravitational acceleration, measured in meters per square second.
,
- Initial and final height with respect to zero reference, measured in meters.
Please notice that is the weight of the particle, measured in newtons.
a) If we know that ,
,
and
, then the change in potential energy is:
The change in potential energy of a 3.0 kilograms backpack carried up the stairs.
b) If we know that ,
and
, then the change in potential energy is:
The change in potential energy of a persona with weight 650 newtons that descends the stairs is -2665 joules.
Answer:
1752.14 tonnes per year.
Explanation:
To solve this exercise it is necessary to apply the concepts related to power consumption and power production.
By conservation of energy we know that:
Where,
Production of Power
Consumption of power
Where the production of power would be,
Where,
m = Total mass required
Energy per Kilogram
Efficiency
The problem gives us the aforementioned values under a production efficiency of 45%, that is,
Replacing the values we have,
Solving for m,
We have the mass in kilograms and the time in seconds, we need to transform this to tons per year, then,
tonnes per year.