Answer:

Explanation:
The electrostatic potential energy for pair of charge is given by
U=1/4π∈₀×(q₁q₂/r)
Hence for a system of three charges the electrostatic potential energy can be found by adding up the potential energy for all possible pairs or charges.For three equal charges on the corners of an equilateral triangle,the electrostatic potential energy is given by:
U=1/4π∈₀×(q²/r)+1/4π∈₀×(q²/r)+1/4π∈₀×(q²/r)
U=3×1/4π∈₀×(q²/r)
Substitute given values
So
The resistance of the sample is 
Explanation:
The relationship between resistance of a material and temperature is given by the equation

where
is the resistance at the temperature 
is the temperature coefficient of resistance
For the sample of nickel in this problem, we have:
when the temperature is 
While the temperature coefficient of resistance of nickel is

Therefore, the resistance of the sample when its temperature is

is

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Answer:
a) according to Faraday's law
, b) creating a faster movement, placing more turns on coil
Explanation:
a) The voltage is induced in the coil by the relative movement between it and the magnet, therefore according to Faraday's law
E = - d (B A) / dt
In this case, the magnet is involved, so the value of the magnetic field varies with time, since the number of lines that pass through the loop changes with movement.
This voltage creates a current that charges the battery
b) There are several ways to increase the voltage
* creating a faster movement, can be done by the user
* placing more turns on the coil, must be done by the manufacturer
The average speed of the ant is 0.276 cm/s and the average velocity is 0.136 cm/s.
The correct answer is option D.
In the given graph, we can deduce the following;
- the total time of the motion, = 1 mins + 45 s = 60 s + 45 s = 105 s
The average speed of the ant is calculated as;

The total distance from the graph is calculated as follows;
- first horizontal distance from 2 cm to 8 cm = 8 - 2 = 6 cm
- first upward distance from 3 cm to 5 cm = 5 - 3 = 2 cm
- second horizontal distance from 8 cm to 6 cm = 8 - 6 = 2 cm
- second upward distance from 5 cm to 12 cm = 12 - 5 = 7 cm
- third horizontal distance from 6 cm to 13 cm = 13 - 6 = 7 cm
- fourth downward distance from 12 cm to 9 cm = 3 cm
- final horizontal distance from 13 cm to 15 cm = 2cm
The total distance = (6 + 2 + 2 + 7 + 7 + 3 + 2) cm = 29 cm

The average velocity is calculated as the change in displacement per change in time.
The displacement is the shortest distance between the start and end positions.
- This shortest distance is the straight line connecting the start and end position. Call this line P
- From the end position at x = 15 cm, draw a vertical line from y = 9 cm, to y = 3 cm. The displacement = 9 cm - 3 cm = 6 cm
- Also, draw a horizontal line from start at x = 2 cm to x = 15 cm. The displacement = 15 cm - 2 cm = 13 cm
Notice, you have a right triangle, now calculate the length of line P.
↓end
↓
↓ 6cm
↓
start -------------13 cm------------
Use Pythagoras theorem to solve for P.

The average velocity of the ant is calculated as;

Thus, the average speed of the ant is 0.276 cm/s and the average velocity is 0.136 cm/s.
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