Question

In which of the following activities is zero work done?

A) walking down a hill
B) pushing a bicycle from school to home
C) holding a sleeping baby
D) playing a piano
E) riding on a sled that is coasting to a stop

Answer 1

@CarlosGP

Answer 2

i think C and D since the net displacement in both these activities should be 0.

Answer 3

I thought about those too but I can only choose one.

Answer 4

then maybe i'd go with D coz i can confirm that the net disp here will 0. i can't vouch for option C.

Answer 5

@Daenio i'm i right on not....

Answer 6

the case in C is the same as a rock at rest on ground. but the work done here IS zero.

Answer 7

ITs C....

Answer 8

@AhsanAJ97 Why would you bother asking me that? LOL. I'm trying to figure out the answer too by gaining a better understanding by asking others.

Answer 9

A)walking down a hill. There is work done
B)pushing a bicycle from school to home. If school and home ar at the same level, then there is no work done except to overcome friction forces
C)holding a sleeping baby. You need to lift the baby up, which means increasing the potential energy and hence work done
D)playing a piano. When hitting the keys, small hammers are lifted to hit the strings to finally remain in the same position. There are frictions to overcome though
E)riding on a sled that is coasting to a stop. There is a negative acceleration and then, there is work

I findthe questions quite tricky. Any could be and any could not be

Answer 10

C) Was my initial response.

Answer 11

C) b'coz u r holding the baby ... not lifting him so its my answer

Answer 12

unless you are rocking the baby ;)

Answer 13

haha ...not funny at all @CarlosGP

Answer 14

To me, it would be the bycicle because it is clear that the movement is perpendicular to gravitational force and scalar product would be ZERO, then no work.

Answer 15

in that case, the displacement is in the direction of the force u're applying in pushing the bike. so that's the force we have to consider. not gravity.

Answer 16

Assuming there are frictions, you are right, otherwise I would only need to give the bike an initial speed and would not need to apply any force for the speed would be maintained. It would be an impulse, instantaneous, without displacement (zero work) to increase its movement. As I said, quite tricky questions

Answer 17

yea, they are vague. then i think i'll go with C as well. assuming ur explanation to cancel out D, C is the only option left.

Answer 18

Well, I have two baby daughters and I can assure you it is a lot of work but this is a horse of a diffrent color...

Answer 19

lol! yes, it is. and i can not even imagine the amount of work [non-physics] it takes in option C!

Answer 20

Whatever the option, please keep us informed and get the rationale for the answer

Answer 21

A) walking down a hill=>Displacement holds some value so no
B) pushing a bicycle from school to home =>Displacement holds some value so no
C) holding a sleeping baby =>Displacement is 0,so F x S =0
D) playing a piano =>Possible,since when you play piano,the key comes back to its initial position,so displacement is 0,hence Work done = 0,That is what I assume.
E) riding on a sled that is coasting to a stop==>Displacement holds some value so no

Answer 22

the question is not correct... because is neccesary some asumptions

Answer 23

THE ANSWER IS C)!!!

Answer 24

great! so our conclusions were correct! was there any explanation provided to support that answer?

Answer 25

Nope.