Practice Questions

Q21.Starting at temperature 300K, one mole of an ideal diatomic gas (γ = 1.4) is first compressed adiabatically from volume V1 to V2 = V116 . It is then allowed to expand isobarically to volume 2V2 . If all the processes are the quasi-static then the final temperature of the gas (in oK ) is (to the nearest integer) ___________. →

Q21.A particle is moving along the x -axis with its coordinate with time t given by x(t) = 10 + 8t −3t2. Another particle is moving along the y -axis with its coordinate as a function of time given by y(t) = 5 −8t3. At t = 1 s, the speed of the second particle as measured in the frame of the first particle is given as √v. Then v(in m s−1) is ___________.

Q21.A small block starts slipping down from a point B on an inclined plane AB, which is making an angle θ with the horizontal section BC is smooth and the remaining section CA is rough with a coefficient of friction μ. It is found that the block comes to rest as it reaches the bottom (point A) of the inclined plane. If BC = 2AC , the coefficient of friction is given by μ = k tanθ . The value of k is ....... JEE Main 2020 (02 Sep Shift 1) JEE Main Previous Year Paper

Q21.The distance x covered by a paritcle in one dimensional motion varies with time t as x2 = at2 + 2bt + c . If the acceleration of the particle depends on x as x−n , where n is an integer, the value of n is _________

Q21.A cricket ball of mass 0. 15 kg is thrown vertically up by a bowling machine so that it rises to a maximum height of 20 m after leaving the machine. If the part pushing the ball applies a constant force F on the ball applies a constant force F on the ball and moves horizontally a distance of 0. 2 m while launching the ball, the value of F(in N) is (g = 10 m s−2)

Q22.A circular disc of mass M and radius R is rotating about its axis with angular speed ω1 . If another stationary disc having radius R and same mass M is dropped co-axially on to the rotating disc. Gradually both discs 2 attain constant angular speed ω2 . The energy lost in the process is p% of the initial energy. Value of p is ______

Q22.A thin rod of mass 0. 9 kg and length 1 m is suspended, at rest, from one end so that it can freely oscillate in the vertical plane. A particle of move 0. 1 kg moving in a straight line with velocity 80 m s−1 hits the rod at its bottom most point and sticks to it (see figure). The angular speed (in rad s−1) of the rod immediately after the collision will be …………

Q22.Two bodies of the same mass are moving with the same speed, but in different directions in a plane. They have a completely inelastic collision and move together thereafter with a final speed which is half of their initial velocities of the two bodies (in degree) is -

Q22.An asteroid is moving directly towards the centre of the earth. When at a distance of 10R ( R is the radius of the earth) from the centre of the earth, it has a speed of 12 km s−1. Neglecting the effect of earth's atmosphere, what will be the speed of the asteroid when it hits the surface of the earth (escape velocity from the earth is 11.2 km s−1) ? Give your answer to the nearest integer in km s−1 __________.

Q22.An electric field E = 4xˆi −(y2 + 1)ˆjN/C passes through the box shown in figure. The flux of the electric field through surfaces ABCD and BCGF are marked as ϕI and ϕII respectively. The difference between (ϕI −ϕII) is (in Nm2/C ) ____________.

Q22.An engine operates by taking a monatomic ideal gas through the cycle shown in the figure. The percentage efficiency of the engine is close to

Q22.A person of 80 kg mass is standing on the rim of a circular platform of mass 200 kg rotating about its axis at 5 revolutions per minute (rpm). The person now starts moving towards the centre of the platform. What will be the rotational speed (in rpm ) of the platform when the person reaches its centre....

Q22.The change in the magnitude of the volume of an ideal gas when a small additional pressure ΔP is applied at a constant temperature, is the same as the change when the temperature is reduced by a small quantity ΔT at constant pressure. The initial temperature and pressure of the gas were 300 K and 2 atm respectively. If |ΔT| = C|ΔP| then value of C in (K/ atm) is __________

Q22.A force F = (ˆi 3ˆk) m will be √x N −m. The value of x is.......... (ˆi + 2ˆj + ˆk)

Q22.An massless equilateral triangle EFG of side 'a' (As shown in figure) has three particles of mass m situated at its vertices. The moment of inertia of the system about the line EX perpendicular to EG in the plane of EFG is N ma2 where N is an integer. The value of N is ___________ . 20

Q22.An engine takes in 5 moles of air at 20 °C and 1 atm, and compresses it adiabatically to 1/10th of the original volume. Assuming air to be a diatomic ideal gas made up of rigid molecules, the change in its internal energy during this process comes out to be XkJ. The value of X to the nearest integer is:

Q22.One end of a straight uniform 1m long bar is pivoted on horizontal table. It is released from rest when it makes an angle 30o from the horizontal (see figure). Its angular speed when it hits the table is given as √n rad s−1 , where n is an integer. The value of n is ____________

Q22.A non-isotropic solid metal cube has coefficients of linear expansion as: 5 × 10−5/oC along the x-axis and 5 × 10−6/oC along the y and the z-axis. If the coefficient of volume expansion of the solid is C × 10−6/oC then the value of C is _____________

Q22.A body A of mass m = 0.1 kg has an initial velocity of 3ˆi m s−1 . It collides elastically with another body B of the same mass which has an initial velocity of 5ˆj m s−1 . After the collision, A moves with a velocity m s−1 . The energy of B after the collision is written as 10x J. The value of x is →v= 4(ˆi +ˆj)

Q23.A Carnot engine operates between two reservoirs of temperatures 900K and 300K . The engine performs 1200J of work per cycle. The heat energy (in J ) delivered by the engine to the low temperature reservoir, in a cycle, is _____________ JEE Main 2020 (07 Jan Shift 1) JEE Main Previous Year Paper

Q23.A closed vessel contains 0.1 mole of a monoatomic ideal gas at 200 K. If 0.05 mole of the same gas at 400 K is added to it, the final equilibrium temperature (in K) of the gas in the vessel will be close to ______

Q23.Three containers C1, C2 and C3 have water at different temperatures. The table below shows the final temperature T when different amounts of water (given in liters) are taken from each container and mixed (assume no loss of heat during the process) JEE Main 2020 (08 Jan Shift 2) JEE Main Previous Year Paper C1 C2 C3 T 1l 2l −− 60oC −− 1l 2l 30oC 2l −− 1l 60oC 1l 1l 1l θ The value of θ (in oC to the nearest integer) is___________

Q23.In a meter bridge experiment S is a standard resistance. R is a resistance wire. It is found that balancing length is l = 25cm. If R is replaced by a wire of hall length and half diameter that of R of same material, then the JEE Main 2020 (09 Jan Shift 2) JEE Main Previous Year Paper balancing distance l' (in cm ) will now be ______________.

Q23.If minimum possible work is done by a refrigerator in converting 100 grams of water at 0 °C to ice, how much heat (in calories) is released to the surroundings at temperature 27 °C (Latent heat of ice = 80 Cal / gram) to the nearest integer?

Q23.A one metre long (both ends open) organ pipe is kept in a gas that has double the density of air at STP. Assuming the speed of sound in air at STP is 300 m/s, the frequency difference between the fundamental and second harmonic of this pipe is __________ Hz. JEE Main 2020 (08 Jan Shift 1) JEE Main Previous Year Paper