An electric wall clock has a second hand 15 cm long. at the tip of his hand, what is the magnitude of the velocity?
1 answer:
The velocity of the tip of the second hand is 0.0158 m/s
Explanation:
First of all, we need to calculate the angular velocity of the second hand.
We know that the second hand completes one full circle in
T = 60 seconds
Therefore, its angular velocity is:
Now we can calculate the velocity of a point on the tip of the hand by using the formula
where
is the angular velocity
r = 15 cm = 0.15 m is the radius of the circle (the distance of the point from the centre of rotation)
Substituting,
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Answer:
b. Decreases
Explanation:
The total resistance of a series circuit is equal to the sum of the individual resistances:
(1)
Therefore, as we add more lamps, the total resistance increases (because we add more positive tems in the sum in eq.(1).
The current in a circuit is given by Ohm's law:
where V is the voltage provided by the power source and is the total resistance. We notice that the current, I, is inversely proportional to the total resistance: therefore, when more lamps are added to the series circuit, the total resistance increases, and therefore the current in the circuit decreases.
The total time is 6.45 s
Explanation:
The motion of the car is a uniformly accelerated motion, so we can use suvat equations.
In the first part,
(initial velocity)
(acceleration)
(time of the first part)
So, we can find the velocity of the car after the first part, by using
This is therefore the initial velocity of the second part:
(acceleration in the second part)
(final velocity)
And therefore,
So, the total time is
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