Home
Class 11
PHYSICS
A child sits stationary at one end of a ...

A child sits stationary at one end of a long trolley moving u8niformly with a speed V on a smooth horizontal floor. If the child gets up and runs about on the trolley in any manner, what is the speed of the CM of the trolley + child ) system ?

A

System remains unchanged

B

Increase

C

decreases

D

increases or decrease

Text Solution

Verified by Experts

The correct Answer is:
A
Promotional Banner

Similar Questions

Explore conceptually related problems

A child is standing at one end of a long trolley moving with a speed v on a smooth horizontal track. If the child starts running towards the other end of the trolley with a speed u, the centre of mass of the system (trolley + child) will move with a speed :

A child is standing at one end of a long trolley moving with a speed v on a smooth horizontal track. If the child starts running towards the other end of the trolley with a speed u, the centre of mass of the system (trolley + child) will move with a speed :

A long belt is moving horizontally with a speed of 5 km/h. A child is running on belt to and fro with a speed of 9 km/h with respect to belt between his father and mother located 50 m apart on the belt. For an observer on a stationary platform outside, what is the speed of the child running opposite to the direction of the belt ?

A trolly of mass 200kg moves with a uniform speed of 36 km // h on a frictionless track. A child of mass 20kg runs on the trolly from one end to the other (10m away) with a speed of 4m//s relative to the trolly in a direction opposite to the trolly's motion and jumps out of the trolly. How much has teh trolly moved from the time the child begins to run ?

A spring is kept compressed by a small trolley of mass ring 0-5 kg lying on a smooth horizontal surface as shown in the adjacent Fig. When the trolley is released, it is found to move at a speed = 2 m s^(-1) . What potential energy did the spring poses when compressed?

A child playing with a long rope ties one end holds the other. The rope is stretched taut along the horizontal. The child shakes the end he is holding, up and down, in a sinusoidal manner with amplitude 10 cm and frequency 3 Hz. Speed of the wave is 15 m//s and, at t=0 , displacement at the child's end is maximum positive. Assuming that there is no wave reflected from the fixed end, so that the waves in the rope are plane progressive waves, answer the following quetions. (Also assume that the wave propagates along the positive x-direction.) Phase difference between the child,s end and a point 2.5m from the child's end will be

A child playing with a long rope ties one end holds the other. The rope is stretched taut along the horizontal. The child shakes the end he is holding, up and down, in a sinusoidal manner with amplitude 10 cm and frequency 3 Hz. Speed of the wave is 15 m//s and, at t=0 , displacement at the child's end is maximum positive. Assuming that there is no wave reflected from the fixed end, so that the waves in the rope are plane progressive waves, answer the following quetions. (Also assume that the wave propagates along the positive x- direction.) A wave function that describe the wave in the given sutuation is

On a long horizontally moving belt, a child runs to and fro with a speed 9 kmh^(-1) ( with respect to the belt) between his father and mother located 50m a part on the moving belt. The belt moves with a speed of 4 kmh^(-1) . For an observer on a stationery platform outside, what is the (i) speed of the child running in the direction of motion of the belt? (ii) speed of the child running opposite to the direction of motion of the belt? (iii) time taken by child in (i) and (ii) ? which of the answers alter if motion is viewed by one of the parents?

A uniform bar of length 12 L and mass 48 m is supported horizontally on two smooth tables as shown in the figure. A small moth (an insect) of mass 8m is sitting on end A of the rod and a spider (an insect) of mass 16 m is sitting on the other end B . Both the insects start moving towards each other along the rod with moth moving at speed 2v and the spider at half of this speed. They meet at a point P on the rod and the spider eats the moth. After this the spider moves with a velocity v//2 relative to the rod towards the end A . The spider takes negligible time in eating the insect. Also, let v = L//T , where T is a constant having value 4 sec .The speed of the bar after the spider eats up the moth and moves towards A is

a. A rail road flat car of mass M can roll without friction along a straight horizontal track . Initially, a man of mass m is standing on the car which is moving to the right with speed v_(0) . What is the change in velocity of the car if the man runs to the left so that his speed relative to the car is v_(rel) just before he jumps off at the left end? b. If there are n men each of mass m on the car, should they all run and jump off together or should they run and jump one by one in order to give a greater velocity to the car?