A ductile metal wire has resistance R. What will be the resistance of this wire in terms of R if it is stretched to three times
1 answer:
Answer:
9R
Explanation:
We know that the resistance is .
If we stretch the wire to a new length L2 = 3L, the cross-sectional area will also change. If the cross-sectional area doesn't change throughout the wire, we can say that:
Volume = L*A = 3L * A2 being A2 the new area after stretching the wire.
Since the volume remains the same we conclude that A2 = A/3
With this information, we calculate the new resistance:
Since , and by simple inspection of the previous equation, we get:
<em>R2 = 9*R</em>
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Answer:
108 km
Explanation:
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1 m = 3.28 ft
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or in kilometers,
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so the difference between the two altitudes is
To develop the problem it is necessary to apply the kinematic equations for the description of the position, speed and acceleration.
In turn, we will resort to the application of Newton's second law.
PART A) For the first part we look for the time, in a constant acceleration, knowing the speeds and the displacement therefore we know that,
Where,
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V = Velocity
t = Time
In this case there is no initial displacement or initial velocity, therefore
Clearing for time,
PART B) This is a question about the impulse of bodies, where we turn to Newton's second law, because:
F = ma
Where,
m=mass
a = acceleration
Acceleration can also be written as,
Then
Negative symbol is because the force is opposite of the direction of moton.
PART C) Acceleration through kinematics equation is defined as
The gravity is equal to 0.8, then the acceleration is