If `F__(ext) = 0`, the c.m. of a system moves with ________ velocity.

A block of mass 15 kg is placed on a long trolley. The coeffcient os static friction between the block and the trolley is 0.18. The trolley accelerates from rest with 0.5 m s^-2 for 20 s and then moves with uniform velocity. Discuss the motion of the block as viewed by:- an observer moving with the trolley.

What is the momentum of an object of mass m moving with velocity v ?

Show that for an isolated system, centre of mass moves with a uniform velocity along a straight path.

Twelve wires of equal lengths are connected in the form of a skelton cube which is moving with a velocity vecv in direction of magnetic field vecB . Find the e.m.f. in each arm of the cube.

Two objects of masses 100 g and 200 g are moving along the same line and direction with velocities of 2 m/s and 1 m/s, respectively. They collide and after the collision , the first object moves at a velocity of 1.67 m /s Determine the velocity of the second object.

Fill in the blanks: If a function f has a local maximum at x = c and f" (c ) < 0, then f' (c ) is equal to __________.