Two discs are rotating about their respective axes, which are normal to the discs and pass through their centres. Disc \(D_1\) has a \(2\) kg mass and \(0.2\) m radius and an initial angular velocity of \(50~\text{rad} ~\text{s}^{-1}.\) Disc \(D_2\) has a \(4\) kg mass, \(0.1\) m radius and an initial angular velocity of \(200~\text{rad} ~\text{s}^{-1}.\) The two discs are brought into contact face to face, with their axes of rotation coincident. The final angular velocity (in \(\text{rad} ~\text{s}^{-1}\)) of the combined system is:
1. \(60\)
2. \(100\)
3. \(120\)
4. \(40\)
1. \(60\)
2. \(100\)
3. \(120\)
4. \(40\)
Subtopic: Angular Momentum |
77%
Level 2: 60%+
NEET - 2013
Hints
The fluid is in streamlined flow through a horizontal pipe with a variable cross-sectional area. Which of the following statements is correct?
| 1. | The velocity is maximum at the narrowest part of the pipe, and pressure is maximum at the widest part of the pipe. |
| 2. | Both the velocity and pressure are maximum at the narrowest part of the pipe. |
| 3. | Both the velocity and pressure are maximum at the widest part of the pipe. |
| 4. | The velocity is minimum at the narrowest part of the pipe, and the pressure is minimum at the widest part of the pipe. |
Subtopic: Equation of Continuity |
69%
Level 2: 60%+
NEET - 2013
Hints
An electromagnetic wave of frequency \(\nu=3.0\) MHz passes from a vacuum into a dielectric medium with relative permittivity \(\varepsilon =4.0.\) Then:
| 1. | wavelength is doubled and frequency becomes half |
| 2. | wavelength is halved and frequency remains unchanged |
| 3. | wavelength and frequency both remain unchanged |
| 4. | wavelength is doubled and frequency unchanged |
Subtopic: Properties of EM Waves |
72%
Level 2: 60%+
NEET - 2013
Hints
A particle with total energy \(E\) is moving in a potential energy region \(U(x).\) The motion of the particle is restricted to the region where:
| 1. | \(U(x)<E\) | 2. | \(U(x)=0\) |
| 3. | \(U(x)\leq E\) | 4. | \(U(x)> E\) |
Subtopic: Conservation of Mechanical Energy |
Level 3: 35%-60%
NEET - 2013
Hints
The displacement \(x\) (in \(\text m\)) of a particle of mass \(m\) (in \(\text{kg}\)) moving in one dimension under the action of a force, is related to time \(t\) (in \(\text s\)) by; \(t = (\sqrt x +3 ).\) The displacement of the particle when its velocity is zero will be:
1. \(4~\text m\)
2. zero
3. \(6~\text m\)
4. \(2~\text m\)
1. \(4~\text m\)
2. zero
3. \(6~\text m\)
4. \(2~\text m\)
Subtopic: Instantaneous Speed & Instantaneous Velocity |
89%
Level 1: 80%+
NEET - 2013
Hints
A \(12\) cm wire is given a shape of a right-angled triangle \(\mathrm{ABC}\) having sides \(3\) cm, \(4\) cm and \(5\) cm, as shown in the figure. The resistance between two ends \((\mathrm{AB, BC, CA})\) of the respective sides are measured one by one by a multi-meter. The resistances will be in the ratio:
1. \(9:16:25\)
2. \(27:32:35\)
3. \(21:24:25\)
4. \(3:4:5\)
1. \(9:16:25\)
2. \(27:32:35\)
3. \(21:24:25\)
4. \(3:4:5\)
Subtopic: Combination of Resistors |
Level 3: 35%-60%
NEET - 2013
Hints
Two sources \(\text{P}\) and \(\text{Q}\) produce notes of frequency \(660~\text{Hz}\) each. A listener moves from \(\text{P}\) to \(\text{Q}\) with a speed of \(1\) m/s. If The speed of sound is \(330\) m/s, then number of beats heard by the listener per second will be:
1. \(4\)
2. \(8\)
3. \(2\)
4. zero
1. \(4\)
2. \(8\)
3. \(2\)
4. zero
Level 3: 35%-60%
NEET - 2013
Hints
The de-Broglie wavelength of neutrons in thermal equilibrium at temperature \(T\) is:
| 1. | \(\dfrac{3.08}{\sqrt{T}} ~\mathring{A}\) | 2. | \(\dfrac{0.308}{\sqrt{T}} ~\mathring{A}\) |
| 3. | \(\dfrac{0.0308}{\sqrt{T}} ~\mathring{A}\) | 4. | \(\dfrac{30.8}{\sqrt{T}} ~\mathring{A}\) |
Subtopic: De-broglie Wavelength |
Level 3: 35%-60%
NEET - 2013
Hints
Two Carnot engines A and B are operated in series. Engine \(A\) receives heat from the source at temperature \(T_1\) and rejects the heat to the sink at temperature \(T.\) The second engine \(B\) receives the heat at temperature \(T\) and rejects to its sink at temperature \(T_2\). For what value of \(T\) the efficiencies of the two engines are equal?
| 1. | \(\dfrac{T_1-T_2}{2} \) | 2. | \(T_1 T_2 \) |
| 3. | \(\sqrt{T_1 T_2} \) | 4. | \(\dfrac{T_1+T_2}{2}\) |
73%
Level 2: 60%+
NEET - 2013
Hints
A particle of mass \(m\) oscillates along the \({x}\text-\)axis according to the equation \(x = a {\sin} \omega t.\) The nature of the graph between momentum and displacement of the particle is:
| 1. | circle |
| 2. | hyperbola |
| 3. | ellipse |
| 4. | a straight line passing through the origin |
Subtopic: Types of Motion |
61%
Level 2: 60%+
NEET - 2013
Hints
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