Answer:
circumference= 65/3 cm = 21.67 cm
radius R = 3.45 cm
Explanation:
To calculate the length of the circumference of the cylinder, we divide 650 cm by 30 (the number of times it wrapped exactly around it)
length of circumference= 65/3 cm = 21.67 cm
now use the formula of the circumference length to find the radius (R):
circumference length = 2 * pi * R
65/3 = 2 * pi * R
R = 65 / (6 pi)
R = 3.45 cm
For rotational equilibrium of the door we can say that torque due to weight of the door must be counter balanced by the torque of external force

here weight will act at mid point of door so its distance is half of the total distance where force is applied
here we know that

now we will have


so our applied force is 72.5 N
A big part of the reason that mirrors are seldom if ever used to generate
electricity is the simple fact that there is no way to generate electricity using
mirrors. They are as useless for the purpose as smoke is, although there are
those who have used both items simultaneously to create the impression that
they have succeeded in that attempt.
Answer:
I think it's 2 the photo is hard to tell what they are exactly talking about.