Which planet is known as evening star
1 answer:
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Answer:
Minimum work = 5060 J
Explanation:
Given:
Mass of the bucket (m) = 20.0 kg
Initial speed of the bucket (u) = 0 m/s
Final speed of the bucket (v) = 4.0 m/s
Displacement of the bucket (h) = 25.0 m
Let 'W' be the work done by the worker in lifting the bucket.
So, we know from work-energy theorem that, work done by a force is equal to the change in the mechanical energy of the system.
Change in mechanical energy is equal to the sum of change in potential energy and kinetic energy. Therefore,
Therefore, the work done by the worker in lifting the bucket is given as:
Now, plug in the values given and solve for 'W'. This gives,
Therefore, the minimum work that the worker did in lifting the bucket is 5060 J.
Answer:
undergoes a transition to a quantum state of lower energy
Explanation:
When electrons in an atom move to another quantum state, they emit/absorb a photon according to the following:
- If the electron is moving to a higher energy state, it absorbs a photon (because it needs energy to move to a higher energy level, so it must absorb the energy of the photon)
- if the electron is moving to a lower energy state, it emits a photon (because it releases the excess energy)
In particular, the energy of the absorbed/emitted photon is exactly equal to the difference in energy between the two levels of the electron transition: