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Write all the formulas of Gravitation , Force , Sound of class 9th( CBSE ) with Important concepts
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Answers
Gravitation▶️⬇️⬇️
➡️1. The Law of Orbits: All planets move in elliptical orbits, with the sun at one focus.
2. The Law of Areas: A line that connects a planet to the sun sweeps out equal areas in equal times.
3. The Law of Periods: The square of the period of any planet is proportional to the cube of the semi major axis of its orbit.
➡️F= G x Mm/x^2
➡️value of G is 6.673 × 10^–11N m^2 kg^–2
➡️g = G M/x^2
g = (6.7 × 10–11 N m^2 kg^-2 x 6 × 10^24 kg)/( 6.4 × 10^6 m)^2
➡️g » 9.8 m/s^2
Sound▶️⬇️⬇️
➡️If a particle of air vibrate 100 times in 2 seconds, then the frequency of the wave would be 50 vibrations per second. Unit for frequency is the Hertz (abbreviated Hz).
➡️1 Hertz = 1 vibration/second
➡️Human ear is capable of detecting sound waves with a wide range of frequencies, ranging between approximately 20 Hz to 20 000 Hz
➡️The amount of energy that is transported through a given area of the medium per unit of time is known as the intensity of the sound wave. Intensity is the energy/time/area or power/area.
➡️ Units for the intensity of a sound wave are Watts/meter2.
➡️The speed of a sound wave in air at a temperature of 20 degrees Celsius= 343 m/s
➡️The eardrum amplify sounds with frequencies of approximately 3000 Hz
Force▶️⬇️⬇️
➡️The First Law (The Law of Inertia) :
➡️Every body continues in a state of rest or uniform velocity in a straight line, unless an external force acts on it.
➡️The Second Law of Motion : The Second Law describes what will happen if there is a force.
When an external, unbalanced force acts on an object, the object will accelerate in the same direction of the force.
F=ma
➡️Don't forget to turn the mass into kilograms when you solve numerical problems.
➡️For every action force there is an equal and opposite reaction force.
Action: the tires on a car push on the road… Reaction: the road pushes on the tires.
Action: while swimming, you push the water backwards... Reaction: the water pushes you forward
@skb
Explanation:
Given tan(A+B)=\sqrt{3}
3
i don't know
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⟹A+B=60∘⋯(1)
tan(A−B)=\sqrt[1]{3}
1
3
⟹A−B=30∘⋯(2)
(1)+(2)⟹2A=90∘⟹A=45∘
Put A value in (1)
⟹B=60∘−45∘=15∘