A listener at rest and heard a sound from a car when away from him and frequency decrease 10% . Calculate the velocity of the car.

A stone is dropped from a rising balloon at a height of 75 m above the ground. It reaches the ground in 6 seconds. Calculate the velocity of the balloon just at the moment when the stone is dropped.

An electron is released from rest in a uniform electric field of magnitude 5xx10^(-4)N/C . Calculate the acceleration of the electron.

At each of the stations A and B a siren its surrounding with a constant of frequency pf 250 Hz.A cyclist from A proceeds towards B with a velocity 12km/hr and hears 5 beats per second.Calculate the velocity of sound.

A pump extracts water from 50m depth and ejects per sec 10 kg water with a velocity of 10m/s.Calculate is power.

In a cold climate water gets forzen causing damage to the radiator of a car. Ethylene glycol is used as an antifreezing agent for the purpose. Calculate the amount of ehtylene glycol to be added to 4kg of water to prevent it from freezing at -6^@C ( K_f for water = 1.85 K mol^(-1) kg)

In a reaction 2A rarr P the Conc of A decreases from 0.5molL^(-1) to 0.4molL^(-1) in 10 sec. Calculate the rate of the reaction.

A spring balance is graduated from O to 16 kg. When is reads 16 kg the spring is stretched by 10 cm. A body suspended from the spring is found to oscillate vertically with a frequency 2 oscillations per second. What the weight of the body ?

A bullet of mass 10 g is fired from a gun with a velocity of 800ms^-1 .After passing through a mud wall 100cm thick its velocity drops to 100ms^-1 .Calculate the average resistance offered by the wall.

A siren is fitted on a car going towards a vertical wall at a speed of 36 kmh^(-1) . A person standing on the ground behind the car, listeners to the siren sound coming directly from the source as well as that coming after reflection from the wall. Calculate the apparant frequencies of both the sounds. Velocity of sound 340ms^(-1) , frequency of the siren 500Hz.

Two aeroplane A and B are approaching each other and their velocities are 108 km/hr and 144 km/hr respectively.The frequency of a note emitted by Aas heard by the passenger in B is 1170 Hz.Calculate the frequency of the note heard by the passenger in A.[velocity of sound 350 m(s)^-1 ].