Identify the false' statement from the following
Work-energy theorem is not independent of Newton's second law
Work-energy theorem holds in all inertial frames
Work done by friction over a closed path is zero
No potential energy can be associated with friction
A particle is acted upon by a force F which varies with position x as shown in figure. If the particle at x = 0 has kinetic energy of 25 J, then the kinetic energy of the particle at x =16 m is
45 J
30 J
70 J
135 J
Two springs P and Q of force constants kp and kQ are stretched by applying forces of equal magnitude. If the energy stored in Q is E, then the energy stored in P is
E
2E
A rod of mass m and length l is made to stand at an angle of 60° with the vertical. Potential energy of the rod in this position is
mgl
If an object of mass mis taken from the surface of earth (radius R) to a height 2R, then the work done is
2 mgR
mgR
C.
Work done
Substituting h = 2R, we get
A particle of mass m carrying charge q is kept at rest in a uniform electric field E and then released. The kinetic energy gained by the particle, when it moves through a distance y is
qEy
qEy2
qE2y
A particle acted upon by constant forces and is displaced from the point to the point . The total work done by the forces in SI unit is
20
40
50
30
Two bodies A and B have masses 20 kg and 5 kg respectively. Each one is acted upon by a force of 4 kg-wt. If they acquire the same kinetic energy in times tA and tB, then the ratio is
2
The height of the dam, in a hydroelectric power station is 10 m. In order to generate 1 MW of electric power, the mass of water (in kg) that must fall per second on the blades of the turbines is
106
105
103
104
A spring gun of spring constant 90 N/cm is compressed 12 cm by a ball of mass 16 g. If the trigger is pulled, the velocity of the ball is
50 ms-1
9 ms-1
90 ms-1
60 ms-1