Is the component perpendicular to the surface on contact of the contact force <span />
Answer:
Explanation:
Given
mass of book(m)=2.1 kg
height up to which book is lifted is (h)2.2 m
height of person 
Potential energy of book relative to ground=mgh

(b)PE w.r.t to person head =mg(h-h0)

work done by person in lifting box 2.2 m w.r.t floor
Word done =Potential Energy of box relative to floor=45.2 J
The correct answer for this question is this one: C) 2.5s. T<span>he period and frequency of a water wave if 4.0 complete waves pass a fixed point in 10 seconds is that 2.5 s
</span>
Here are the following choices:
<span>A) 0.25s
B) 0.40s
C) 2.5s
D) 4.0s</span>
In a direct current the electric charge flows in one direction.
in an alternating the electric charge changes in its direction periodically.
Answer:
Around 44.01g.
Explanation:
One mole of carbon dioxide molecules has a mass of 44.01g, while one mole of sodium sulfide formula units has a mass of 78.04g.