Menu Close

There-are-two-parallel-planes-each-inclined-to-the-horizontal-at-an-angle-A-particle-is-projected-from-a-point-mid-way-between-the-foot-of-the-two-planes-so-that-it-grazes-one-of-the-planes-and-st




Question Number 18271 by Tinkutara last updated on 01/Aug/17
There are two parallel planes, each  inclined to the horizontal at an angle θ.  A particle is projected from a point mid  way between the foot of the two planes  so that it grazes one of the planes and  strikes the other at right angle. Find  the angle of projection of the projectile.
$$\mathrm{There}\:\mathrm{are}\:\mathrm{two}\:\mathrm{parallel}\:\mathrm{planes},\:\mathrm{each} \\ $$$$\mathrm{inclined}\:\mathrm{to}\:\mathrm{the}\:\mathrm{horizontal}\:\mathrm{at}\:\mathrm{an}\:\mathrm{angle}\:\theta. \\ $$$$\mathrm{A}\:\mathrm{particle}\:\mathrm{is}\:\mathrm{projected}\:\mathrm{from}\:\mathrm{a}\:\mathrm{point}\:\mathrm{mid} \\ $$$$\mathrm{way}\:\mathrm{between}\:\mathrm{the}\:\mathrm{foot}\:\mathrm{of}\:\mathrm{the}\:\mathrm{two}\:\mathrm{planes} \\ $$$$\mathrm{so}\:\mathrm{that}\:\mathrm{it}\:\mathrm{grazes}\:\mathrm{one}\:\mathrm{of}\:\mathrm{the}\:\mathrm{planes}\:\mathrm{and} \\ $$$$\mathrm{strikes}\:\mathrm{the}\:\mathrm{other}\:\mathrm{at}\:\mathrm{right}\:\mathrm{angle}.\:\mathrm{Find} \\ $$$$\mathrm{the}\:\mathrm{angle}\:\mathrm{of}\:\mathrm{projection}\:\mathrm{of}\:\mathrm{the}\:\mathrm{projectile}. \\ $$
Commented by Tinkutara last updated on 17/Jul/17
Commented by Tinkutara last updated on 01/Aug/17
The point is midpoint of the line joining  feet of the two planes (as not shown in  the figure).
$$\mathrm{The}\:\mathrm{point}\:\mathrm{is}\:\mathrm{midpoint}\:\mathrm{of}\:\mathrm{the}\:\mathrm{line}\:\mathrm{joining} \\ $$$$\mathrm{feet}\:\mathrm{of}\:\mathrm{the}\:\mathrm{two}\:\mathrm{planes}\:\left(\mathrm{as}\:\mathrm{not}\:\mathrm{shown}\:\mathrm{in}\right. \\ $$$$\left.\mathrm{the}\:\mathrm{figure}\right). \\ $$
Commented by ajfour last updated on 03/Aug/17
I have a method but that fetches  correct  answer but in another form.  φ=tan^(−1) [tan θ+(1/( (√2)))(tan θ+cot θ)].
$$\mathrm{I}\:\mathrm{have}\:\mathrm{a}\:\mathrm{method}\:\mathrm{but}\:\mathrm{that}\:\mathrm{fetches} \\ $$$$\mathrm{correct}\:\:\mathrm{answer}\:\mathrm{but}\:\mathrm{in}\:\mathrm{another}\:\mathrm{form}. \\ $$$$\phi=\mathrm{tan}^{−\mathrm{1}} \left[\mathrm{tan}\:\theta+\frac{\mathrm{1}}{\:\sqrt{\mathrm{2}}}\left(\mathrm{tan}\:\theta+\mathrm{cot}\:\theta\right)\right]. \\ $$

Leave a Reply

Your email address will not be published. Required fields are marked *