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Three blocks m, m and M are kept on a frictionless floor as shown in figure. The left most block is given velocity v towards right. All the collisions between the blocks are perfectly inelastic. The loss in kinetic energy after all the collisions is 5/6^th of initial kinetic energy. The ratio of M/m will be:

a) 1/8 b) 1/4 c) 4 d) 2 Answer: (c) \(\begin{array}{l}\frac{mu}{2m+M}= V_{f}\end{array} \) \(\begin{array}{l}K_{f} = \frac{1}{6}K_{1}\end{array} \) \(\begin{array}{l}\frac{1}{2} \frac{P^{2}}{2m+M}= \frac{1}{6}\frac{1}{2}\frac{P^{2}}{m}\end{array}... View Article

If temperature difference T₁ – T₂ is 120°C. The temperature difference between points A & B is

a) 30 b) 45 c) 60 d) 75 Answer: (b) Effective resistance between A and B is

If current in a current carrying wire is 1.5A, number of free electrons per unit volume is 8 x10²⁸m³ and area of cross section is 5 mm² . Drift velocity of electrons will be

a) 0.02 mm/s b) 2 mm/s c) 0.2 mm/s d) None of these Answer: (a) i = e n A... View Article

A conducting loop of resistance 10Ω and area 3.5 x 10 ^-3m ² is placed in uniform and time varying magnetic field B = 0.4 sin (50πt). The Charge passing through the loop in t = 0 to t = 10 ms is:

a) 140 µC b) 70 µC c) 280 µC d) 100 µC Answer: (a) \(\begin{array}{l}Q=\frac{\Delta \phi }{R}\end{array} \) \(\begin{array}{l}\varepsilon =\frac{d... View Article

Two radioactive elements A & B have initially activity 10 curie & 20 curie respectively. If A has twice the no. of moles as that of B. The decay constant λ_A & λ_B can be;

a) (10, 5) b) (5, 20) c) (20, 10) d) (50, 100) Answer: (b) Conceptual λN = A \(\begin{array}{l}\frac{\lambda _{A}}{\lambda... View Article

Charge Q is uniformly distributed over a ring of radius R. The height h, on the axis of the ring at which electric field is maximum

a) R /√2 b) R/2 c) R d) None of these Answer: (a) E (along) axis of circular coil =... View Article

Magnetic field at point O is

a) 1.5 x 10– 5 b) 10– 5 c) 2 x 10– 5 d) 10– 4 Answer: (b) Solution: B0... View Article

Initially block of mass M is at rest on a frictionless floor and the spring is in relaxed condition A constant force is applied on the block as shown in the figure. The maximum velocity of block is:

a) F/√mK b) 2F /√mK c) F/2√ mK d) F √2mK Answer: (a) Maximum speed is at equilibrium where F=kx⇒x=... View Article

The velocity of a particle v at any instant is [latex]vec{v}=yhat{i}+xhat{j}[/latex]. The equation of trajectory of the particle is:

a) x 2 + y2 = constant b) y 2 = x 2 + constant c) xy = constant d)... View Article

A planet of mass m having angular momentum L is revolving around the sun. The aerial velocity of the planet will be

a) L/m b) L/2m c) 2L/m d) L/4m Answer: (b) For small dθ, dA = (1/2) r2 dθ (dA/dt) =... View Article

Initially, an object is kept at a distance of 10 cm from the convex lens and a sharp image is formed at 10 cm ahead of the lens on the screen. Now a glass plate of µ = 1.5 cm and thickness 1.5 cm is placed between object and lens. The distance by which the screen be shifted to get a sharp image on the screen will be:

a) 1.1 cm b) 0.55 cm away from the lens c) 0.55 cm towards the lens d) 5 cm Answer:... View Article

For path ABC, Heat given to the system is 60 J and work done by the system is 30 J. For path ADC, work done by the system is 10J. The heat given to the system for path ADC is

a) 100 J b) 80 J c) 40 J d) 60 J Answer: (c) Change in Int energy should be... View Article

A block of mass 10 kg is kept on a rough inclined plane as shown in figure. The coefficient of friction between the block and the surface is 0.6. Two forces of magnitudes 3N & P Newton are acting on the block as shown figure. If friction on the block is acting upwards then minimum value of P for which the block remains at rest is:

a) 64 N b) 32 N c) 12 N d) 3 N Answer:(b) Upward force = Downward force mg sinθ... View Article

The correct sequence of reagents for the following conversion will be :

Answer: (3)

3-Methyl-pent-2-ene on reaction with HBr in presence of peroxide forms an addition product. The number of possible stereoisomers for the product is :

1) Two 2) Four 3) Six 4) Zero Answer: (2) Since the product (X) contains two chiral centres and it... View Article

Which of the following, upon treatment with tert-BuONa followed by addition of bromine water, fails to decolourize the colour of bromine?