when we climb work is done. When we walk on a plane surface, work is not done. Why is it so?

Question

When we move our fingers or hands , orr when we sit, work is not done. when we move an object, work is done. When we climb up the stairs, work is not done. Why is it so?

Answer 1

the formula for wrk done is FScos(theta) when we apply force in the upward or downward direction(in case of opposing gravity) perpendicular to direction of displacement theta becomes equal to 90 degrees , and cos90 is zero. hence work done is zero.

Answer 2

The answer arch v21 is best but I would like to add to it. The angle theta here is between the direction of the force and the direction of the displacement.

You said, "When we move our fingers or hands , orr when we sit, work is not done". That's not very accurate. If you move your fingers or hands up, you do work. What Shaz said about potential energy is true. When you raise your hand you give it potential energy. If you let your hand/arm go limp and fall on an egg, the egg would break.

You said, "when we move an object, work is done". That may or may not be true. If you move the object horizontally, in the general case no work is done. (I had to say "in the general case" because there could be a spring or other means of resisting that horizontal move that would store energy.) If you move it vertically, work is done.

You said, "When we climb up the stairs, work is not done." That's wrong. The work you did gave your body potential energy. Yu could convert that energy to kinetic by jumping over the railing down onto a table and break it.

Answer 3

In physics, if this is the angle you are looking at, work done generally is interchangeble with the word energy.

If you climb a hill you use chemical and kinetic energy.
If you walk on a plane you use the same type of energy but you body will use less of it. Whereas climbing or pushing things you use more energy as you are fighting against friction and gravity.

So in all the situations described work is done, but to a differing level.

Answer 4

Work is defined as the line integral of a scalar product of force and displacement vectors. For the simple case, this is the product of force and the distance over which it is applied. When you move your finger, a muscle is applying work to cause the finger to move. When you sit, your body is applying a force to the chair, but the displacement is zero so the work is zero. When you descend the stairs, the work you apply is negative, since the displacement direction is opposite that of the force.

Note that this is one, narrow definition of work. If you hold a brick still in front of you, you do no work on the brick. But your muscles consume fuel in order to continually apply that force. That fuel consumption depends primarily on the force applied, not the distance over which it is applied.

Answer 5

Because when climbing or picking up objects..you are changing the potential energy..as opposed to walking level or just moving there has been no change in potential energy

Answer 6

Work is Force x Distance. In all the situations you describe Work is being done.

Answer 7

this is a retard question