Question

Which one of the following is NOT an example of work being done?

The moon orbiting Earth
Pushing a box from the bottom of a hill to the top of the hill
Pulling a sled across a field covered with snow
Lifting a bookbag off the floor

Answer 1

If the path of moon around the earth is assumed to be circular, the direction of the centripetal force of the earth and the direction of displacement of moon at any point are perpendicular to each other
W=F.s
W=Fscos@
@=90
Therefore Work done is 0

Answer 2

so it was the moon orbiting earth?

Answer 3

help anyone?
is the moon orbiting earth is correct?

Answer 4

yeap!!

Answer 5

help please

Answer 6

according to definition of work done.
W = F (dot) R (where R is radial vector) = FRcos\(\theta\)
which says that for work to be done, Force and Distance traveled have to be in same direction. But in this case, \(\theta\) is 90 so no work is done.

Answer 7

so it was the moon orbit the earth right

Answer 8

yes 99.99% right.

Answer 9

100.01%

Answer 10

thanks everyone

Answer 11

and then some :)

Answer 12

on average 100% sure.

Answer 13

thumbs up