The energy transfer diagram represents the energy of a person diving into a pool.
2 answers:
The correct answer is:
<span>A) 1000 J
In fact, energy cannot be destroyed nor created: this means that the total energy of the person must remain constant.
The initial energy of the person is U=8000 J, in form of gravitational potential energy. When he jumps and dives into the pool, this energy is converted into kinetic energy (K, 7000 J) and partially into thermal energy, Et. The final energy of the person, sum of kinetic energy and thermal energy, must be equal to the initial energy:
</span>
<span>from which we can find the thermal energy:
</span>
<span>
</span>
<span>A) 1000 J
In fact, energy cannot be destroyed nor created: this means that the total energy of the person must remain constant.
The initial energy of the person is U=8000 J, in form of gravitational potential energy. When he jumps and dives into the pool, this energy is converted into kinetic energy (K, 7000 J) and partially into thermal energy, Et. The final energy of the person, sum of kinetic energy and thermal energy, must be equal to the initial energy:
</span>
<span>from which we can find the thermal energy:
</span>
</span>
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Answer:
Both of them reach the lake at the same time.
Explanation:
We have equation of motion s = ut + 0.5at²
Vertical motion of James : -
Initial velocity, u = 0 m/s
Acceleration, a = g
Displacement, s = h
Substituting,
s = ut + 0.5 at²
h = 0 x t + 0.5 x g x t²
Vertical motion of John : -
Initial velocity, u = 0 m/s
Acceleration, a = g
Displacement, s = h
Substituting,
s = ut + 0.5 at²
h = 0 x t + 0.5 x g x t²
So both times are same.
Both of them reach the lake at the same time.