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 [tex](h_0)1.6 m[/tex]
Potential energy of book relative to ground=mgh
[tex]PE=2.1\times 9.8\times 2.2=45.276 J[/tex]
(b)PE w.r.t to person head =mg(h-h0)
[tex]=2.1\times 9.8\times (2.2-1.6)=12.348 J[/tex]
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
