A man lifts a 20-kg box from the ground up to the top of a 30-m high building. The box is initially at rest, but it
travels at 4 m/s when it reaches the top of the building. How much work is done by the man in lifting the box?
A. 5840 J
B. 160 J
C. 2400 J
D. 6000 J
E. 6160 J
answer is still...
F= m.a
W= F.d
use thıs two fırst to get the value
K=1/2 M v^2
and add thıs one
f=20x(9,8)=196N
w=196.20=3920N
k=1/2.20.(4^2)=160N
we should add thıs two value because final velocity of the partıcle is 4 m/s.
answer=160+3920N=4080N
solving by
FUAT MERT AĞARLI