Answer:
a) 0.31 rad/s
b) 100 J
c) 6.67 W
Explanation:
(a) the force would generate a torque of:

According to Newton 2nd law, the angular acceleration would be

It starts from rest, then after 15s it would achieve a speed of

(b) The distance angle swept by it is:

Hence the work by the child

c) Average power to work per time unit

Answer is miles sir your welcome it was simple
All of the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons. As you move down the table, every row adds an orbital.
The concept of power is given by the relationship between intensity and area, that is to say that power is defined as

Our values are given under the condition of,


The power is proportional to the Area, and in turn, we know that the Area of a circle is the product between
times the radius squared, therefore the power is proportional to the radius squared.

For both panels we would have to



Therefore the correct option is option C.9