projectiles formulas
BASIC TERMS use in projectiles formulas
When a particle is projected into the air,
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then the particle is called a projectile.
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the point from which the particle is projected is called the point of projection.
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the angle that the direction in which it is projected makes with the horizontal plane through the point of projection is called the angle of projection;
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the path which the particle describes is called its trajectory;
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the distance between the point of projection and the point where the path meets any plane drawn through the point of projection is its range on the plane;
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the time that elapses before it again meets the horizontal plane through the point of projection is called the time of flight.
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the initial velocity with which the projectile is projected is called the velocity of projection.
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the maximum height reached by a projectile during its motion is called greatest height.
Check out Physics Formulas and NCERT Solutions for class 12 Physics prepared by Physics Wallah.
LIST OF PROJECTILES FORMULA
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Velocity and direction of motion after time ‘t’ v2 = u2 – 2ugt sinα + g2t2 and tanθ =
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Velocity and direction of motion at height ‘h’ v2 = u2 – 2gh and tan θ =
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Greatest height attained by a projectile h =
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Time for the greatest height =
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Time of flight t =
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Range =
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Maximum Range =
Here u : initial velocity of the body
α : Angle of projection
θ : Angle which the velocity of the projectile at a certain point makes with the horizontal (It is the tangent to the path of the projectile at the point)
g : acceleration due to gravity
Note:
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The path of a projectile is a parabola, given by y = x tan α -
i.e.
with vertex ≡
latus rectum =
and height of directrix =
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The velocity at any point is equal in magnitude, to that which would be acquired by a particle in falling freely from the directrix to that point.
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There are two direction for a given range and velocity and also two times for a given height.
Range and Time of Flight on an Inclined Plane:
If from a point on a plane which is inclined at an angle β to the horizon, a particle is projected with a velocity u, at an angle α with the horizontal, in a plane passing through the normal to the inclined plane and the line of greatest slope, then
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Time of flight, T=
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Range =
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Maximum range up the plane =
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Range, time of flight and maximum range down the plane is obtained by putting –β for β.
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For a given range and given velocity there are two different directions of projection which are equally inclined to the direction of projection for maximum range.
Example :If the maximum range of a particle is R, show that the greatest height attained is . A body can throw a ball 60 meters. How long is the ball in the air, and what height does it attain.
Detail Explanation : Let the particle be projected with a velocity v at an angle α with the horizontal.
Horizontal range =
Greatest height =
The range is maximum where sin2α = 1 ⇒ α = 45°
⇒ R = ⇒ H =
Now R = 60 metres ⇒ h = 15 metres
Now time t of flight = =
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t2 =
⇒ t = 3.5 sec aprox.