The earliest stage of a star’s life before it begins to undergo fusion is known as:
1 answer:
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The final kinetic energy of the ball is 2.45 J
Explanation:
We can solve this problem by using the law of conservation of energy.
In absence of frictional effect, the mechanical energy of the apple must be conserved during the fall. So we can write:
where :
is the initial potential energy, at the top
is the initial kinetic energy, at the top
is the final potential energy, at the bottom
is the final kinetic energy, at the bottom
By explicing the potential energy, we can rewrite the equation as:
where:
m = 0.5 kg is the mass of the apple
is the acceleration of gravity
is the initial height
is the final height
The initial kinetic energy is zero, since the ball starts from rest:
Therefore we can solve the equation for , the final kinetic energy of the ball:
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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.
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