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A sounding body emitting a frequency of 150 Hz is dropped from a height. During its fall under gravity it crosses a balloon moving upwards with a constant velocity of 2m/s one second after it started to fall. The difference in the frequency observed by the man in balloon just before and just after crossing the body will be: (given that -velocity of sound = 300m/s; g = 10m/s2 )

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A sounding body emitting a frequency of 150 Hz is dropped from a height. During its fall under gravity it crosses a balloon moving upwards with a constant velocity of 2m/s one second after it started to fall. The difference in the frequency observed by the man in balloon just before and just after crossing the body will be:

Given that -velocity of sound = 300m/s; g = 10m/s2.

(A) 4

(B) 6

(C) 8

(D) 12

Kirti Gulati tag : Physics 16 Apr, 2019 1 Answer 57 views

A passenger is standing d distance away from a bus. The bus begins to move with constant acceleration a. To catch the bus, the passenger runs at a constant speed u towards the bus. What must be the minimum speed of the passenger so that he may catch the bus?

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A passenger is standing d distance away from a bus. The bus begins to move with constant acceleration a. To catch the bus, the passenger runs at a constant speed u towards the bus. What must be the minimum speed of the passenger so that he may catch the bus?

Anonymous User tag : Physics 15 Apr, 2019 1 Answer 88 views

A driver takes 0.30 s to apply the brakes after he sees a need for it. This is called the reaction time of the driver. If he is driving a car at a speed of 54 km/h and the brakes cause a deceleration of 5.0m/s2, find the distance travelled by the car after he sees the need to put the brakes on ?

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A driver takes 0.30 s to apply the brakes after he sees a need for it. This is called the reaction time of the driver. If he is driving a car at a speed of 54 km/h and the brakes cause a deceleration of 5.0m/s2, find the distance travelled by the car after he sees the need to put the brakes on ?

Anonymous User tag : Physics 15 Apr, 2019 1 Answer 62 views

The force of repulsion between two point charges is F, when these are at a distance of 1 m. Now the point charges are replaced by spheres of radii 25 cm having the charge same as that of point charges. The distance between their centres is 1 m, then compare the force of repulsion in two cases.

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The force of repulsion between two point charges is F, when these are at a distance of 1 m. Now the point charges are replaced by spheres of radii 25 cm having the charge same as that of point charges. The distance between their centres is 1 m, then compare the force of repulsion in two cases.

Anonymous User tag : Physics 13 Apr, 2019 1 Answer 813 views

A particle is moving along a straight line along x-axis with an initial velocity of 2 m/s towards positive x-axis. A constant acceleration of 0.5 m/s2 towards negative x-axis starts acting on particle at t=0. Find velocity (in m/s) of particle at t = 2s.

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A particle is moving along a straight line along x-axis with an initial velocity of 2 m/s towards positive x-axis. A constant acceleration of 0.5 m/s2 towards negative x-axis starts acting on particle at t=0. Find velocity (in m/s) of particle at t = 2s.

Rahul Kumar tag : Physics 12 Apr, 2019 1 Answer 64 views

A body is thrown up with a speed 49 m/s. It travels 5 m in the last second of its upward journey. If the same body is thrown up with a velocity 98 m/s, how much distance (in m) will it travel in the last second. (g = 10 m/s2)?

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A body is thrown up with a speed 49 m/s. It travels 5 m in the last second of its upward journey. If the same body is thrown up with a velocity 98 m/s, how much distance (in m) will it travel in the last second. (g = 10 m/s2)?

Rahul Kumar tag : Physics 12 Apr, 2019 1 Answer 83 views

A solid sphere of mass M and radius R is surrounded by a spherical shell of same mass M and radius 2R as shown. A small particle of mass m is released from rest from a height h (<<R) above the shell. There is a hole in the shell.

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A solid sphere of mass M and radius R is surrounded by a spherical shell of same mass M and radius 2R as shown. A small particle of mass m is released from rest from a height h (<<R) above the shell. There is a hole in the shell.

Devendra Yadav tag : Physics 12 Apr, 2019 0 Answer 83 views

If the law of gravitation be such that the force of attraction between two particles vary inversely as the 5/2th power of their separation, then the graph of orbital velocity v0 plotted against the distance r of a satellite from the earth's centre on a log-log scale is shown alongside. The slope of line will be

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If the law of gravitation be such that the force of attraction between two particles vary inversely as the 5/2th power of their separation, then the graph of orbital velocity v0 plotted against the distance r of a satellite from the earth's centre on a log-log scale is shown alongside. The slope of line will be

Ashish Yadav tag : Physics 12 Apr, 2019 1 Answer 57 views