Chapter 6: Work, Energy and Power

An electron and a proton are moving under the influence of mutual forces. In calculating the change in the kinetic energy of the system during motion, one ignores the magnetic force of one on another. This is because,

a) the two magnetic forces are equal and opposite, so they produce no net effect

b) the magnetic forces do no work on each particle

c) the magnetic forces do equal and opposite work on each particle

d) the magnetic forces are necessarily negligible

A proton is kept at rest. A positively charged particle is released from rest at a distance d in its field. Consider two experiments; one in which the charged particles is also a proton and in another, a positron. In the same time t, the work done on the two moving charged particles is

A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is

a) constant and equal to mg in magnitude

b) constant and greater than mg in magnitude

c) variable but always greater than mg

d) at first greater than mg, and later becomes equal to mg

A bicyclist comes to a skidding stop in 10 m. During this process, the force on the bicyclist due to the road is 200 N and is directly opposed to the motion. The work done by the cycle on the road is

a) +2000 J

b) -200 J

c) zero

d) -20,000 J

A body is falling freely under the action of gravity alone in a vacuum. Which of the following quantities remain constant during the fall?

During inelastic collision between two bodies, which of the following quantities always remain conserved?

Two inclined frictionless tracks, one gradual and the other steep, meet at A, from where two stones are allowed to slide down from rest, one on each track as shown in the figure. Which of the following statement is correct?

The potential energy function for a particle executing linear SHM is given by
where k is the force constant of the oscillator. For k = 0.5 N/m, the graph of V(x) versus x is shown in the figure. A particle of total energy E turns back when it reaches x = ±xm, then which of the following is correct?

Two identical ball bearings in contact with each other and resting on a frictionless table are hit head-on by another ball bearing of the same mass moving initially with a speed V as shown:

If the collision is elastic, which of the following is a possible result after collision?

A body of mass 0.5 kg travels in a straight line with velocity v = ax^3/2 where a = 5 m^-1/2s^-1. The work done by the net force during its displacement from x = 0 to x = 2 m is

a) 1.5 J

b) 50 J

c) 10 J

d) 100 J