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11.

A small block of mass 1 kg is released from rest at the top of a rough track. The track is a circular arc of a radius of 40 m. The block slides along the track without toppling and a frictional force acts on it in the direction opposite to the instantaneous velocity . The work done in overcoming the friction up to the point Q , as shown in the figure, is 150 J  .(take the acceleration due to gravity , g=10 ms-2)

The magnitude of the normal reaction that acts on the block at the point Q is

A) 7.5 N

B) 8.6 N

C) 11.5 N

D) 22.5 N

12.

A small block of mass 1 kg is released from rest at the top of a rough track. The track is a circular arc of a radius of 40 m. The block slides along the track without toppling and a frictional force acts on it in the direction opposite to the instantaneous velocity. The work done in overcoming the friction up to the point Q, as shown in the figure, is 150 J  . (take the acceleration due to gravity, g=10 ms-2)

The speed of the block when it reaches the point Q is

A) $5ms^{-1}$

B) $10ms^{-1}$

C) $10\sqrt{3}ms^{-1}$

D) $20ms^{-1}$

13.

The radius of the orbit of an electron in a Hydrogen-like atom is 4.5 a0 where a0 is the Bohr radius. Its orbital angular moment is $\frac{3h}{2\pi}$. It is given that h is Planck constant and R is Rydberg constant. The possible  wavelength (s) when the atom de-excites,  is (are)

A) $\frac{9}{32R}$

B) $\frac{9}{16R}$

C) $\frac{9}{5R}$

D) $\frac{4}{3R}$

14.

The figure below shows the variation of specific heat capacity (C)  of a solid as a function of temperature (T). The temperature is increased continuously from 0 to 500 K  at a constant rate. Ignoring any volume change, the following statement (s)  is (are)  correct to a reasonable approximation.

A) the rate at which heat is absorbed in the range 0-100K varies linearly with temperature T

B) heat absorbed in increasing the temperature from 0-100 K is less than the heat required for increasing the temperature from 400-500 K

C) there is no change in the rate of heat absorbtion in the range 400-500K

D) the rate of heat absorption increases in the range 200-300K

15.

Two non- conducting spheres of radii R1 and R2 are carrying uniform volume charge densities +$\rho$ and -$\rho$  respectively, are placed, such that they partially overlap, as shown in the figure. At all points in the overlapping region

A) the electrostatic field is zero

B) the electrostatic potential is constant

C) the electrostatic field is constant in magnitude

D) the electrostatic field has same direction

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