A fat person is standing oa ligh plank floating on a calm lake. The person walks from one end to the other on the plank. His friend sitting on the shore watches him and finds that the person hardly moves any distance because the plank moves basckward about the same distance as the person moves on the plank. Explain.

A man of mass 80 kg stands on a plank of mass 40 kg . The plank is lying on a smooth horizontal floor. Initianlly both are at rest. The man starts walking on the plank towards north and stops after moving a distance of 6 m on the plank. Then

A person moves on a semicircular track of radius 40 m. If he starts at one end of the track and reaches the other end, find the distance covered and magnitude of displacement of the person.

An old person moves on a semi circulasr track of radius 40.0 m during a moirning walk. If he starts at one end of the track and reaches at the other end, find the distance covered and the displacement of the person.

A person writes a letter to four of his friends. He asks each one of them to copy the letter and mail to four different persons with instruction that they move the chain similarly. Assuming that the chain is not broken and that it costs 50 paise to mail one letter. Find the amount spent on the postage when 8th set of letter is mailed.

An object A is kept fixed at the point x= 3 m and y = 1.25 m on a plank p raised above the ground . At time t = 0 the plank starts moving along the +x direction with an acceleration 1.5 m//s^(2) . At the same instant a stone is projected from the origin with a velocity vec(u) as shown . A stationary person on the ground observes the stone hitting the object during its downward motion at an angle 45(@) to the horizontal . All the motions are in the X -Y plane . Find vec(u) and the time after which the stone hits the object . Take g = 10 m//s

In the figure shown, when the persons A and B exhange their position, then (i) the distance moved by the centre of mass of the system is ____. (ii) the plank moves towards_____. (iii) the distance moved by the plank is _________. (iv) the distacne moved by A with respect to ground is _____. (v) the distance moved by B with respect to ground is _____.

Two audio speakers are kept some distance apart and are driven by the same amplifier system. A person is sitting at a place 6.0 m from one of the speakers and 6.4 m from the other. If the sound signal is continuously varied from 500 Hz to 5000 Hz, what are the frequencies for which there is a destructive interference at the place of the listener? Speed of sound in air = 320 ms^-1

A person moves towards north with uniform speed of 15 m/s and cover 16 m. After this he moves towards east and covers 6 m and finallt covers 8 m distance with same speed in south. Find out (i) Distance travelled by person (ii) Displacement of person (iii) Average velocity of person