# Two persons,  of mass 60 kg and  of mass 40 kg, are standing on a horizontal platform of mass 50 kg. The platform is supported on wheels on a horizontal frictionless surface and is initially at rest. Consider the following situations (i) Both  and  jump from the platform simultaneously and in the same horizontal direction (ii) A jumps first in a horizontal direction and after a few seconds  also jumps in the same direction In both the situations above, just after the jump, the person (  or ) moves away from the platform with a speed of 3 m/s relative to the platform and along the horizontal Answer these questions In situation (i), just after both  and  jump from the platform, velocity of centre of mass of the system ( and the platform) is a) 2 m/s b) 6 m/s c) 5 m/s d) None of these

## Question ID - 101226 :- Two persons,  of mass 60 kg and  of mass 40 kg, are standing on a horizontal platform of mass 50 kg. The platform is supported on wheels on a horizontal frictionless surface and is initially at rest. Consider the following situations (i) Both  and  jump from the platform simultaneously and in the same horizontal direction (ii) A jumps first in a horizontal direction and after a few seconds  also jumps in the same direction In both the situations above, just after the jump, the person (  or ) moves away from the platform with a speed of 3 m/s relative to the platform and along the horizontal Answer these questions In situation (i), just after both  and  jump from the platform, velocity of centre of mass of the system ( and the platform) is a) 2 m/s b) 6 m/s c) 5 m/s d) None of these

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Answer Key : (d) -
 (d) Centre of mass will remain at rest because there is no external force on the system of , and platform

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A string with one end fixed on a rigid wall, passing over a fixed frictionless pulley at a distance of 2 m from the wall, has a point mass  of 2 kg attached to it at a distance of 1 m from the wall. A mass  of 0.5 kg is attached to the free end. The system is initially held at rest so that the string is horizontal between wall and pulley and vertical beyond the pulley as shown in Fig. The system is released from the rest from the position as shown

 The ratio of velocity of  and  when  strikes the wall is a) b) c) d)