A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other.
The source is moving with a speed of 19.4 ms−1 at an angle of 60o with the source observer line as shown in the figure.
The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air 330 ms−1), is

Three identical balls are placed on a frictionless horizontal surface touching each other. They stick to each other because of adhesive. Another ball of same radius and mass m is placed over the void created by the three balls. Find the forces applied by the balls kept on the floor to each other if the system remains in equilibrium.

A car loaded with water having total mass 1000 kg moves on a straight horizontal Road starting from rest under the action of a force of 100 Newton. The water spills throw a small hole in the bottom at a rate of 0.1 KG per second the velocity of cart after 300 seconds is nearly.

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