Let original length be L. The new length is therefore 4L.
Let original cross sectional surface area of the wire be equal to πr^2.
This means original volume was L x πr^2 = Lπr^2
The volume is the same but the length is different so 4L x new surface area must be equal to Lπr^2. Let new surface area be equal to Y.
4L x Y = Lπr^2
=> Y = (πr^2 )/ 4
Using the resistivity formula,
R = pL/A. p which is resistivity is a constant so it stays the same
But this time, instead of L we have 4L and instead of πr^2 we have (πr^2)/4.
so the new resistance
= (4Lp)/ {(πr^2)/4}
= 16 (pL)/(πr^2)
= 16 (pL)/A. because πr^2 is A
since pL/A is equal to R from the formula, this is equal to
16 R.
R was 10 ohms
therefore new resistance is 16 x 10 = 160 ohms
Answer:
W = 112.76MJ
Explanation:
the work is:
where 
is the force executed in the direction of the displacement and the d the displacement.
so:
W = 12000Ncos(20)(10000)
we use the cos of the angule because it give us the proyection in the axis x of the force, that means the force in the direction of the displacement.
W = 112.76MJ
The formula used in calculations relating to transformers
is:
<span>Secondary voltage
(Vs)/ Primary voItage (VP) = Secondary turns (nS)/
Primary turns (nP)</span>
Substituting the
given values to find for Vs,
Vs / 120 V = 400
turns / 100 turns
<span>Vs = 480 V</span>
Answer:
The speed with which the pebble strikes the ground is 30.4m/s
Explanation:
Initial velocity (u) = 17.5m/s, height (h) = 31.5m, acceleration due to gravity (g) = 9.8m/s^2
V^2 = u^2 + 2gh = 17.5^2 + 2×9.8×31.5 = 306.25 + 617.4 = 923.65
V^2 = 923.65
V = √923.65 = 30.4m/s
