Which of the following is not an example of zero work?a)The work done by the tension in the string, when a body tied with the string move along a circular pathb)When a horse pulls a cart on a level road.c)The work done by a coolie when he travels on a horizontal platform, with a load on his head.d)When a person holds some amount of load but, does not move from his position.Correct answer is option 'B'. Can you explain this answer?

Question

Answer

W = F.s = F s cos¢
In option a) displacement (s) along circular path is zero. work done = F.s = F.0 = 0.
In option b) both force (F) and displacement applied. work done is not equal to zero (has some work).
In option c) angle between force and displacement is 90'. work done = F.s = F s cos90' = 0.
In option d) displacement travelled by the person is zero. work done = F.s = 0.

Answer

W=F.S=FS cosa in option c,F is perpendicular to S, so W=0 in option d no S soF.S=0

Answer

Why not c be the ans

Answer

B, work done is not zero.

Answer

Ya why not c be the answer

Answer

C

Answer

Explanation:

The work done by a horse pulling a cart on a level road is not an example of zero work.

Work and Zero Work:

Work is defined as the product of force and displacement in the direction of the force. Mathematically, work (W) can be calculated as:

W = F * d * cosθ

Where:
- W is the work done
- F is the force applied
- d is the displacement
- θ is the angle between the force and displacement vectors

Zero work occurs when the force and displacement vectors are perpendicular to each other, i.e., θ = 90° or cosθ = 0. In such cases, no work is done as the force does not contribute to the displacement.

Examples of Zero Work:

a) The work done by the tension in the string, when a body tied with the string moves along a circular path:
- In this case, the tension in the string acts towards the center of the circle, while the displacement of the body is along the tangent of the circle.
- The angle between the tension and displacement vectors is 90°, leading to zero work.

c) The work done by a coolie when he travels on a horizontal platform with a load on his head:
- In this scenario, the force of gravity acting on the load is vertical, while the displacement of the coolie and the load is horizontal.
- Again, the angle between the force and displacement vectors is 90°, resulting in zero work.

d) When a person holds some amount of load but does not move from his position:
- If no displacement occurs, the work done is zero regardless of the force applied.

Why Option B is not an Example of Zero Work:

b) When a horse pulls a cart on a level road:
- In this situation, the force applied by the horse is in the same direction as the displacement of the cart.
- As the force and displacement vectors are parallel, the angle between them is 0°, and cosθ = 1.
- Therefore, work is not zero and can be calculated using the work formula mentioned earlier.

Conclusion:

The work done by the tension in a string when a body moves along a circular path, the work done by a coolie on a horizontal platform with a load, and the work done when a person holds a load without displacement are examples of zero work. However, when a horse pulls a cart on a level road, work is not zero because the force and displacement vectors are parallel.

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