- 1(current)
Q. No.Air flows past a windmill at a constant speed \(v,\) the area swept by the blades being \(A.\) Assume that the windmill extracts a constant fraction of the energy of the air that flows past it. The power generated by the windmill varies with \(v\) as:
1. \(v^{-1}\)
2. \(v^{1}\)
3. \(v^{2}\)
4. \(v^{3}\)
1. \(v^{-1}\)
2. \(v^{1}\)
3. \(v^{2}\)
4. \(v^{3}\)
Subtopic: Power |
Level 3: 35%-60%
Hints
A car is driven by an engine that delivers constant power (except possibly at the initial instant). If it starts from rest, its displacement varies with time \((t)\) as:
1. \(t\)
2. \(\sqrt t \)
3. \(\dfrac{1}{\sqrt t}\)
4. \(t\sqrt t \)
1. \(t\)
2. \(\sqrt t \)
3. \(\dfrac{1}{\sqrt t}\)
4. \(t\sqrt t \)
Subtopic: Power |
52%
Level 3: 35%-60%
Hints
A particle (mass: \(0.5~\text{kg}\)) moves along a straight line under the action of forces, and its velocity (\(v\)) varies with position (\(x\)) as shown in the figure:
The power delivered to the particle by all the forces acting on it, when it is at \(x=1~\text{m}\), is:
1. \(4~\text{W}\)
2. \(-4~\text{W}\)
3. \(2~\text{W}\)
4. \(-2~\text{W}\)
The power delivered to the particle by all the forces acting on it, when it is at \(x=1~\text{m}\), is:
1. \(4~\text{W}\)
2. \(-4~\text{W}\)
3. \(2~\text{W}\)
4. \(-2~\text{W}\)
Subtopic: Power |
56%
Level 3: 35%-60%
Hints
At the moment of projection of a projectile (mass: \(m\), initial speed: \(u\), angle of projection: \(\theta\)) the power due to the force of gravity is:
1. \(-mg u\)
2. \(mg u \cos\theta\)
3. \(-mgu \cos^2\theta\)
4. \(-mg u \sin\theta\)
1. \(-mg u\)
2. \(mg u \cos\theta\)
3. \(-mgu \cos^2\theta\)
4. \(-mg u \sin\theta\)
Subtopic: Power |
59%
Level 3: 35%-60%
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Hints
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A water pump lifts water from a well which is \(20~\text{m}\) deep at a rate of \(60~\text{kg/min}\) – with negligible kinetic energy Take \(g = 10~\text{m/s}^2\). The losses in the pump are \(20\%\). The power of the pump is:
1. \(200~\text{W}\)
2. \(250~\text{W}\)
3. \(2000~\text{W}\)
4. \(500~\text{W}\)
1. \(200~\text{W}\)
2. \(250~\text{W}\)
3. \(2000~\text{W}\)
4. \(500~\text{W}\)
Subtopic: Power |
59%
Level 3: 35%-60%
Please attempt this question first.
Hints
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A particle of mass \(m\) moves in three dimensions with a velocity \(\vec{v}\) and an acceleration \(\vec{a}\) (not necessarily constant). The dot product \(\vec {a}\cdot \vec{v}\) is proportional to:
| 1. | work done by all forces |
| 2. | work done by centripetal forces |
| 3. | power due to all forces |
| 4. | power due to centripetal forces |
Subtopic: Power |
59%
Level 3: 35%-60%
Hints
- 1(current)
Q. No.
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