Question

@Mashy @Mashy

Answer 1

A rigid body of mass m kg is lifted uniformly by a man to a height of one metre in 30 sec. Another man lifts the same mass uniformly to the same height in 60 sec. The work done on the body against gravitation by them are in ratio

(A)

1 : 2

(B)

1 : 1

(C)

2 : 1

(D)

4 : 1

Answer 2

haha.. i always ask this question in class :D..

Answer 3

what do you think?

Answer 4

cool! hehe

Answer 5

i tried but i failed i was getting 4:1

Answer 6

who do you think did more work?

Answer 7

focus the relation between work and power .. :)

Answer 8

uh , i say both did equal work

Answer 9

exactly.. then if both did equal work
what should be the ratio of their work done?

Answer 10

1:1 !!

Answer 11

yup..

Answer 12

But how will you prove it algebraicly i need to show steps man

Answer 13

ok.. how much work did the first person do?

Answer 14

How do y

Answer 15

actually g

Answer 16

get that

Answer 17

@oksuz_ can u walk him through that... i have to step out for a while!

Answer 18

I used s=1/2 at^2

Answer 19

For displacement

Answer 20

@oksuz_

Answer 21

@sidsiddhartha

Answer 22

you can just use E=mgh

Answer 23

you know g,m and h ..

Answer 24

So,
mgh:mgh
lol
1:1

Answer 25

yep :)

Answer 26

Can we do it without using mgh formula

Answer 27

the work done by gravity depends only on linear distance between initial point and final point. Therefore it does not depend on the trajectory and the time.. The best way to use E=mgh formula..