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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Hello!
<em>a) What is the change in momentum</em>?
The change of the momentum is the velocity, because the velocity is reduced to zero.
We can calculate the aceleration, applicating the formula:
Like you see, the final velocity will be zero, so:
Like you see, the aceleration applicate by superman is of <u>-10 m/s^2.</u>
If the aceleration is negattive, means the velocity will decrease.
<em>b.) What is the magnitud of the force wich superman exerts on the train?</em>
For calculate the force applicate for superman, lets applicate the second law of Newton:
Lets replace and resolve it:
F = 8x10^3 kg * (-10 m/s^2)
F = 8000 kg * (-10 m/s^2)
F = -80 000 N
The force applicated is of <u>-80000 Newtons.</u>
When the force is negative means the force applicated in the another direction of the object what is traveling.