Give condition for no work?

1.	Give condition for no work?
Answer» In physics no work is said to be done, if (a) The applied force (F) is zero. A body moving with uniform velocity on a smooth surface has some displacement but no external force so in the case work done is zero. (b) The displacement (S) is zero. A labourer standing with a load on his head doe no work. (c)The angle between force and displacement (θ) is π/2 rad or 90° . Then cos θ = cos 90° = 0. Thus work done is also zero. In circular motion, instantaneous work done is always zero because of this reason. (d) The change in kinetic energy (∆KE) is zero.

Answer»

In physics no work is said to be done, if

(a) The applied force (F) is zero. A body moving with uniform velocity on a smooth surface has some displacement but no external force so in the case work done is zero.

(b) The displacement (S) is zero. A labourer standing with a load on his head doe no work.

(c)The angle between force and displacement (θ) is π/2 rad or 90° . Then cos θ = cos 90° = 0. Thus work done is also zero. In circular motion, instantaneous work done is always zero because of this reason.

(d) The change in kinetic energy (∆KE) is zero.

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