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
D.
Centre of the mass of the rod lies at the midpoint and when the rod is displaced through an angle 60° it rises to point B.
From the figure
Then potential energy of the rod in this position is
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
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