#grade 9 physics

[rajansmoorthy]

Sonic Resonance: Unlocking the Speed of Sound with Air Column Magic!

Experiment using Resonance Air column Using the principle of resonance, the resonance air column equipment measures the sound velocity in room temperature air. Resonance happens at particular air column lengths when a tuning fork with a known frequency is struck and held above the air column. The velocity of sound in air can be computed by measuring these lengths. Speed of sound: Resonance air…

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[rajansmoorthy]

Calculating Force: Magnitude and Direction in Physics

Question: A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 ms-1 to 3.5 ms-1 in 25 sec. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force? Solution: Calculating the Acceleration: Initial velocity of the body $${u=2 \ \frac{m}{s}}$$ Final velocity of the body $${v=3.5 \ \frac {m}{s}}$$ Time taken t=25…

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[rajansmoorthy]

Calculating Stopping Time for a Body under Constant Retarding Force

Question: A constant retarding force of 50 N is applied to a body of mass 20 Kg moving initially with a speed of 15 ms-1 .How long does the body take to stop? Solution: Stopping time calculation: Calculating the acceleration: $${Acceleration =\frac{Force}{Mass}}$$ $${Acceleration =\frac {50 \ N}{20 \ Kg}}$$ $${Acceleration= 2.5 \ \frac{m}{s^2}}$$ Retardation: Retardation is -2.5…

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[rajansmoorthy]

Circular Orbit Speed Calculation for Satellite: 42250 Km Radius in 24 Hours

Question: An artificial satellite is moving in a circular orbit of radius 42250 Km.Calculate its speed if it takes 24 hours to revolve around the earth. Solution: Circular orbit speed calculation: $${Speed =\frac{Distance \ travelled}{Time \ taken}}$$ Speed of the artificial satellite=$${\frac{Distance \ travelled \ by \ the \ satellite \ in \ one \ revolution}{Time \ taken \ by \ the \…

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[rajansmoorthy]

Gravity Motion Problem: Analyzing Velocity and Distance

A body is thrown up with a velocity 100 ms-1. It travels 5 m in the last second of its journey.If the same body is thrown up with a velocity 200 ms-1, how much distance (in metre) will it travel in the last second? (take g=10 ms-2) Question: Solution: Distance travelled in the last second when thrown with a velocity 200 ms-1 Gravity numerical-Velocity and distance Initial velocity u=200…

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[rajansmoorthy]

Rocket Vertical Acceleration: Calculating Time to Reach Maximum Point

Question: A rocket is fired vertically up from the ground with a resultant vertical acceleration of 15 ms-2.The fuel is finished in 1 minute and it continues to move up.What is the time taken for the rocket to reach its maximum point? (take g =10 ms-2 ) Solution: Vertical acceleration- calculating time to reach maximum point Rocket vertical acceleration Total time taken for the rocket to…

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[rajansmoorthy]

Ratio of Time Taken to Drop Bodies from Different Heights

Question: Two bodies of different masses m1 and m2 are dropped from two different heights a and b.What is the ratio of time taken by the two bodies to drop through these distances. Solution: Ratio of time taken Ball dropped – Sign convention The two objects are striking the ground with velocities v1 and v2 respectively. $${v_1=\sqrt{2gh_1}}$$ $${v_2=\sqrt{2gh_2}}$$ Time taken by the two…

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[rajansmoorthy]

Projectile Motion: Angle for Equal Height and Range

Question What is the value of angle of projection for which the height of the projectile (H) and the range (R)of the projectile are the same? Solution: Height and range Maximum height of the projectile (H) Maximum height of the projectile Height of the projectile (H) $${H=\frac{u^2 \sin^2\theta}{2g}}$$ Range of the projectile $${R=\frac{u^2\sin 2…

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