5 points
1 answer:
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Answer:
The system loses 90 kJ of heat
Explanation:
We can answer the question by using the 1st law of thermodynamics, which states that:
where
is the change in internal energy of the system
is the heat absorbed by the system (positive if absorbed, negative if released by the system)
is the work done by the system (positive if done by the system, negative if done by the surrounding on the system)
In this problem, we have:
is the work done (negative, because it is done by the surrounding on the system)
is the increase in internal energy
Using the equation above, we can find Q, the heat absorbed/released by the system:
And the negative sign means that the system has lost this heat.
Both require time, but velocity requires displacement and speed requires distance.
Explanation:
Speed and velocity are two different quantities. In fact:
- Speed is a scalar quantity, which gives a measure of how fast an object is moving, regardless of its direction. Therefore, it only has a magnitude, which is given by the ratio between distance covered and time taken:
Therefore, speed does not take into account the direction of motion.
- Velocity, on the other hand, is a vector quantity, so it has magnitude and a direction.
The magnitude of the velocity is given by
where displacement is a vector connecting the initial point with the final point of motion of an object.
The direction of the velocity corresponds to the direction of the displacement.
It must be noted also that in certain situations, the average velocity is zero, while the speed is not zero: for example, for an object completing a circle in a certain time interval, its speed is not zero, while its velocity is zero (because the object returns to the starting point, so the displacement is zero.
Therefore, the correct answer is
Both require time, but velocity requires displacement and speed requires distance.
Learn more about speed and velocity:
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