A 4kg box accelerated from rest by a force across the floor at a rate of 2m/s^2 for 7 seconds. What is the net work done on the
box?
2 answers:
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Answer:
B) 2I
Explanation:
The equation that relates voltage, current and resistance is V=RI.
The equation for the resistance of a material in terms of its resistivity, length and cross-sectional area is
In this case, the length is divided by 2 while keeping its resistivity (since it's the same material) and area, which means the resistance gets divided by 2. Then, looking at the equation I=V/R and keeping V constant, one deduces that since the resistance now is half than before then current now must be twice as before.
This is all intuitive in fact, cuting a homogeneous resistor in half and leaving the rest of the variables constant makes twice as easy for the electrons to cross the conductor, thus twice the current (one has to know that all the variables involved behave linearly, as the equations show).