Motion in a Plane - Result Question 31

34. The horizontal range and the maximum height of a projectile are equal. The angle of projection of the projectiles is :

[2012]

(a) θ=tan1(14)

(b) θ=tan1

(c) θ=tan1(2)

(d) θ=45

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Solution:

  1. (b) Horizontal range,

R=u2sin2θg

Maximum height,

H=u2sin2θ2g

According to the condition,

R=H

u2sin2θg=u2sin2θ2g

2sinθcosθ=sin2θ2

2cosθ=sinθ2

cotθ=14

tanθ=4

θ=[tan1(4)]

In case of projective motion range R is n times the maximum height H

i.e., R=nHu2sin2θg=nu2sin2θ2g

Tanθ=4n Angle of projection θ=tan1(4n)



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