Answer:
...do
Explanation:
24. While measuring the length of a book, the reading of the scale at one end is 5.0 cm and at the other end is 20.5
cm. What is the length of the book in mm?
25. Explain the modifications
We know that arc length (x(t)) is given with the following formula:

Where r is the radius of the barrel. We must keep in mind that as barrel rolls its radius decreases because less and less tape is left on it.
If we say that the thickness of the tape is D then with every full circle our radius shrinks by d. We can write this down mathematically:

When we plug this back into the first equation we get:

We must solve this quadratic equation.
The final solution is:

It is rather complicated solution. If we asume that the tape has no thickness we get simply:
Answer:
1.) Current = 213.33A
2.) Potential difference = 3200 V
Explanation:
Given that
Number of electrons n = 4 x 10^21 electrons
Resistance R = 15 ohm
Time t = 3 s
From the definition of current ;
Current is the rate of flow of changes. That is,
Current I = Q/t
Where
Q = 4 × 10^21 × 1.6 × 10^-19
Q = 460C
Current I = 460/3
Current I = 213.33 A
Using Ohms law which state that
V = IR
Substitute the resistance R and current I into the formula above
Potential difference V = 213.3 × 15
Potential difference V = 3200 V