On a horizontal frictionless surface, a small block with mass 0.200 kg has a collision with a block of mass 0.400 kg. Immediatel
y after the collision, the 0.200 kg block is moving at 12.0 m/s in the direction 30° north of east and the 0.400 kg block is moving at 13.0 m/s in the direction 53.1° south of east. Use coordinates where the x-axis is east and the y-axis is north. (a) What is the total kinetic energy of the two blocks after the collision (in joules)
1 answer:
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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>