Physics-
General
Easy
Question
A flywheel has moment of inertia 4 kg-m2 and has kinetic energy of 200 J. Calculate the number of revolutions is makes before coming to rest if a constant opposing couple of 5N-m is applied to the flywheel -
- 12.8 rev
- 24 rev
- 6.4 rev
- 16 rev
The correct answer is: 6.4 rev
W = KE or () = 
I2
(2n) = I2
Related Questions to study
Physics-
A circular disc A of radius r is made from an iron plate of thickness t and another circular disc B of radius 4r is made from an iron plate of thickness t/4. The relation between the moments of inertia IA and IB is-
A circular disc A of radius r is made from an iron plate of thickness t and another circular disc B of radius 4r is made from an iron plate of thickness t/4. The relation between the moments of inertia IA and IB is-
Physics-General
Physics-
Three thin uniform rods each of mass M and length L and placed along the three axis of a Cartesian coordinate system with one end of each rod at the origin. The M.I. of the system about z-axis is-
Three thin uniform rods each of mass M and length L and placed along the three axis of a Cartesian coordinate system with one end of each rod at the origin. The M.I. of the system about z-axis is-
Physics-General
Physics-
The moment of inertia depends upon-
The moment of inertia depends upon-
Physics-General
Physics-
Three rings, each of mass P and radius Q are arranged as shown in the figure. The moment of inertia of the arrangement about YY' axis will be-
Three rings, each of mass P and radius Q are arranged as shown in the figure. The moment of inertia of the arrangement about YY' axis will be-
Physics-General
Physics-General
Physics-
Two discs have same mass and thickness. Their materials are of densities 1 and 2. The ratio of their moment of inertia about central axis will be -
Two discs have same mass and thickness. Their materials are of densities 1 and 2. The ratio of their moment of inertia about central axis will be -
Physics-General
Physics-
In an arrangement four particles, each of mass 2 gram are situated at the coordinate points (3, 2, 0), (1, –1, 0), (0, 0, 0) and (–1, 1, 0). The moment of inertia of this arrangement about the Z-axis will be-
In an arrangement four particles, each of mass 2 gram are situated at the coordinate points (3, 2, 0), (1, –1, 0), (0, 0, 0) and (–1, 1, 0). The moment of inertia of this arrangement about the Z-axis will be-
Physics-General
Physics-
A stone of mass 4 kg is whirled in a horizontal circle of radius 1m and makes 2 rev/sec. The moment of inertia of the stone about the axis of rotation is-
A stone of mass 4 kg is whirled in a horizontal circle of radius 1m and makes 2 rev/sec. The moment of inertia of the stone about the axis of rotation is-
Physics-General
Physics-
A particle, moving along a circular path has equal magnitudes of linear and angular acceleration. The diameter of the path is : (in meters)
A particle, moving along a circular path has equal magnitudes of linear and angular acceleration. The diameter of the path is : (in meters)
Physics-General
Physics-
.A pair of parallel conducting rails lie at right angles to a uniform magnetic field of 
as shown in the fig. Two resistors 
and 
are to slide without friction along the rail. The distance between the conducting rails is 
. Then
.A pair of parallel conducting rails lie at right angles to a uniform magnetic field of as shown in the fig. Two resistors and are to slide without friction along the rail. The distance between the conducting rails is . Then
Physics-General
Physics-General
Physics-
In a magnetic field of 
, area of a coil changes from 
to 
without changing the resistance which is 
. The amount of charge that flow during this period is
In a magnetic field of , area of a coil changes from to without changing the resistance which is . The amount of charge that flow during this period is
Physics-General
Physics-
In an induction coil, the secondary e.m.f. is
In an induction coil, the secondary e.m.f. is
Physics-General
Physics-
Three solenoid coils of same dimension, same number of turns and same number of layers of winding are taken. Coil 1 with inductance 
was wound using a Mn wire of resistance 11
;Coil 2 with inductance 
was wound using the similar wire but the direction of winding was reversed in each layer; Coil 3 with inductance 
was wound using a superconducting wire. The self-inductance of the Coils 
are
Three solenoid coils of same dimension, same number of turns and same number of layers of winding are taken. Coil 1 with inductance was wound using a Mn wire of resistance 11;Coil 2 with inductance was wound using the similar wire but the direction of winding was reversed in each layer; Coil 3 with inductance was wound using a superconducting wire. The self-inductance of the Coils are
Physics-General
Physics-
A rectangular loop has a sliding connector 
of length 
and resistance 
and it is moving with a speed 
as shown. The set-up is placed in a uniform magnetic field going into the plane of the paper. The three currents 
are
A rectangular loop has a sliding connector of length and resistance and it is moving with a speed as shown. The set-up is placed in a uniform magnetic field going into the plane of the paper. The three currents are
Physics-General
Physics-
Flux
(in weber) in a closed circuit of resistance 20
varies with time t (in secon(d) according to equation
The magnitude of the induced current at t =0.25 s is
Flux (in weber) in a closed circuit of resistance 20 varies with time t (in secon(d) according to equationThe magnitude of the induced current at t =0.25 s is
Physics-General
Physics-
The horizontal component of the earth’s magnetic field at a place is 
and the dip is 
. A metal rod of length 
placed in the north-south position and is moved at a constant speed of 
towards the east. The emf induced in the rod will be
The horizontal component of the earth’s magnetic field at a place is and the dip is . A metal rod of length placed in the north-south position and is moved at a constant speed of towards the east. The emf induced in the rod will be
Physics-General
