An ac source is rated at 220V, 50Hz. The time taken for voltage to change from its peak value to zero is
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A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 m/s. To give an initial upward acceleration of 20 m/s^{2}, amount of gas ejected per second to supply needed thrust will be (g=10 m/s^{2})
A particle of mass m is executing uniform circular motion on a path of radius r. If p is the magnitude of its linear momentum. The radial force acting on the particle is
The energy of a photon of light with wavelength 5000Å is approximately 2.5eV. This way the energy of an Xray photon with wavelength 1Å would be
Electric field at the centroid of a triangle carrying q charge at each corner is
A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is
Two NOT gates are connected at the two inputs of a NAND gate. This combination will behave like
A body is projected at such an angle that the horizontal range is three times the greatest height. The angle of projection is
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer
Assertion(A):Two bodies 1 and 2 exerting forces on each other.Force exerted on the body 1 by body 2 is F^{ →} 12 and that exerted on the body 2 (by body 1) is F^{ →} 21 . Then F^{ → } 12 = − F^{ → } 21 .
Reason(R):Force F^{ → } 12 is of action and force F ^{→} 21 is of reaction.
The M.I. of a body about the given axis is 1.2 kg x m^{2} initially the body is at rest. In order to produce a rotational kinetic energy of 1500 joule an angular acceleration of 25 rad/sec^{2 } must be applied about that axis for a duration of
The radionuclide ^{56}Mn is being produced in a cyclotron at a constant rate P by bombarding a manganese target with deutrons. ^{56}Mn has a half life of 2.5 hours and the target contains large number of only the stable manganese isotope ^{55}Mn. The reaction that produces ^{56}Mn is:
^{55}Mn+d→^{56}Mn+P
After being bombarded for a long time, the activity of ^{56}Mn becomes constant equal to 13.86×10s^{−1}. (Use ln2 = 0.693; Avogadro number = 6×10^{23} atomic weight of ^{56}Mn = 56gm/mole)
Q. After a long time bombardment, number of ^{56}Mn nuclei present in the target depends upon
(a) The number of ^{56}Mn nuclei present at the start of the process
(b) Half life of the ^{56}Mn
(c) The constant rate of production P
A circular road of radius 1000 m has banking angle 45º. The maximum safe speed of a car having a mass 2000 kg will be, if the coefficient of friction between tyre and road is 0.5 :
A bob of mass m, suspended by a string of length ℓ_{1} is given a minimum velocity required to complete a full circle in the vertical plane. At the highest point, it collides elastically with another bob of mass m suspended by a string of length ℓ_{2}, which is initially at rest. Both the strings are massless and inextensible. If the second bob, after collision acquires the minimum speed required to complete a full circle in the vertical plane, the ratio ℓ_{1}/ℓ_{2} is.
A ring of radius 2m weights 100 kg. Its having pure rolling motion on a horizontal floor so that its centre of mass has a speed of 20 cm/s. If work done to stop it is xJ. Then x will be
2 kg ice at – 20°C is mixed with 5 kg water at 20°C. Then final amount of water in the mixture would be :
Given specific heat of ice = 0.5cal/g°C, specific heat of water = 1 cal/g°C, Latent heat of fusion of ice = 80 cal/g. (in kg)
A diode having potential difference 0.5 V across its junction which does not depend on current, is connected in series with resistance of 20 Ω across source. If 0.1 A passes through resistance then what is the voltage of the source :
357 docs148 tests

357 docs148 tests
