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>
No. We aren't the same age as the universe.
Answer:
the number of grains in the ball is 274,848
Explanation:
Given that;
diameter = 0.5 mm
so radius r = 0.25 mm
first we determine the volume of the ball using the following equation;
V = 4/3×πr³
we substitute
V = 4/3×π(0.25)³
V = 0.06544 mm³
Now form table 1.1 "Grain sizes" a metal with grain size number of 12 has about 4,200,000 grains/mm³
so;
Number of grains N = 0.06544 × 4,200,000
N = 274,848 grains
Therefore, the number of grains in the ball is 274,848
Answer:
Explanation:
electrons are a waste product of bacteria living around plant roots – plants discharge organic matter into the soil, which is broken down by bacteria. It is possible to harvest them using motonless electrodes and turn them into electricity, without affecting the plant’s growth in any way.
Answer:
87.5 m/s
Explanation:
The speed of a wave is given by
where
v is the wave speed
is the wavelength
f is the frequency
In this problem, we have
is the frequency
is the wavelength
Substituting into the equation, we find
