If we have to figure air resistance into it, then we don't have enough information to find an answer.
If the air around it is going to have an effect on how it falls, then it'll depend on the thickness of the book, the shape of the book, whether it's a hard-cover or soft-cover, how far the covers stick out past the pages, how smooth or rough the covers are, how bumpy the binding it. and what position you hold it in before you let it go.
(THAT's why we always ignore air resistance, especially when the question is actually about gravity anyway.)
Answer:

Explanation:
The work of force 2 will be given by the vectorial equation
. We know the value of
and have information about its movement, which relates to the net force
.
About this movement we can obtain the acceleration using the equation
. Since it departs from rest we have
.
And then using Newton's 2dn Law we can obtain the net force F=ma, thus we will have 
And we had the work done by force 2 as:

(The sign will be given algebraically since we take positive the direction to the right.)
With our values:

<em>Another (shorter but maybe less intuitive way for someone who is learning) way of doing this would have been to say that the work done by both forces would be equal to the variation of kinetic energy:</em>
<em>
</em>
<em>Which leads us to the previous equation straightforwardly.</em>
Answer:
Because it is the result of two more fundamental units, a derived unit is termed that. For volume, the cubic meter (m³) is the fundamental unit of area. Any number that cannot be measured directly with any equipment is referred to as a derived unit. For example, we can't quantify a substance's density using a rule, scale, or bucket.
OAmalOHopeO
The force the box is exerting on Manuel is the weight of the box, downward:

and this force is perfectly balanced by the constraint reaction applied by Manuel's hand, pushing upward.
Answer:
Part a)
U = 31.25 J
Part b)
U = 312.5 J
Explanation:
Part A)
A spring that requires a force of 50 N to be stretched 0.2 m from its equilibrium position.
So here we have


k = 250 N/m
now the energy stored in the spring is given by



Part B)
A spring that requires 50 J of work to be stretched 0.2 m from its equilibrium position.
So here we know the formula of spring energy as



now by the formula of energy stored in spring


