projectile....

a particle is projected with a velocity 2√gh so tht it just clears two walls of equal height h which r at a distance 2h frm each other. show that the time of passing b/w the walls is 2√h/g.....

2 Answers

62
Lokesh Verma ·

Hint:

Find the velocity of the projectile when it just reaches the top of one of the walls
After which it becomes a projectile with range of 2h

Now can you solve it?

1
fibonacci ·

assume initial projection angle=θ , g=10m/s2
so at first wall you have
vx=√40hcosθ
vy=√40h2sin2θ-20h
so velocity at 1st wall=√40h2-20h
let angle be φ
we have \frac{(40h^2-20h)sin2\phi }{g}=2h
put sin2\phi=2cos^2\phi -1 and get cos\phi =\sqrt{\frac{h}{2h-1}}
so horizontal velocity at 1st wall=√20h=√2gh
distance to travel = 2h
divide distance by speed to get the result

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