Why it is difficult to run fast in sand
2 answers:
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The two ladybugs have same rotational (angular) speed
Explanation:
The rotational (angular) speed of an object in circular motion is defined as:
where
is the angular displacement
t is the time interval considered
Here we have two ladybugs, which are located at two different distances from the axis. In particular, ladybug 1 is halfway between ladybug 2 and the axis of rotation. However, since they rotate together with the disk, and the disk is a rigid body, every point of the disk cover the same angle in the same time
: this means that every point along the disk has the same angular speed, and therefore the two ladybugs also have the same angular speed.
On the other hand, the linear speed of the two ladybugs is different, because it follows the equation:
where r is the distance from the axis: and since the two ladybugs are located at different , they have different linear speed.
Learn more about circular motion:
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Answer: a) 1 b) 61 W c) 61 W
Explanation:
a) The Power Factor (also known as cos φ), is defined by the difference in phase between current and voltage, in a RLC series circuit, and is expressed as follows:
cos φ = R / Z = R /
In resonance, XL =XC, so the circuit behaves like it were purely resistive, so Z=R.
Replacing in the expression for power factor, we have:
cos φ = R/Z = R/R = 1
This means that in resonance, current and voltage are in phase each other.
b) The average power delivered by the source, in resonance, is simply the power dissipated at the resistance R, as follows:
Pavg = V² rms / R = V₀² / √2 / R = 61 W
c) If the circuit remains in resonance, the average power , which does not depends on frequency provided this condition remains, keeps the same, i.e. , 61 W.