16.If a body is lying on a plane whose in-clination with the horizontal is less than the angle of friction, then i) a force is required to move the body upwards ii) a force is required to move the body downward iii) the body will not be in equilibrium The correct answer is

17.Two balls of masses 3 kg and 6 kg are moving with velocities of 4 m/sec and 1 m/sec respectively, towards each other along the line of their centres. After impact the 3 kg ball comes to rest. This can happen only if the coefficient of restitution between the balls is

18.A stone was thrown vertically upwards from the ground with a velocity of 50 m/sec. After 5 seconds another stone was thrown vertically upwards from the same place. If both the stones strike the ground at the same time, then the velocity with which the second stone was thrown should be (Assume g = 10 m/sec2)

19.A light rope is loaded with many equal weights at equal horizontal intervals. The points of suspension on the rope lie on a

20.Cartesian form of the equation of catenary is