anonymous 5 years ago pls help me.. it is possible to project a particle from level ground with a given velocity in 2 possible ways so as to make it pass through a point on the ground at a distance r from the point of projection .The product of time taken to reach this point in the 2 possible ways is then proportional ro a. r b. 1/r

1. anonymous

The answer is a) r. If the particle is thrown at an angle θ with initial velocity u, then r will be $r = u ^{2}\sin2\theta/g ^{2}$ Then, the particle can be thrown with two different angles θ and (pi/2 - θ) to pass through the same point at distance r. Now, the time taken for the particle is $T1 = 2usin \theta/g$ and $T2 = 2usin(\pi/2 - \theta)/g = 2ucos \theta/g$ Now, (T1xT2) is proportional to r.

2. anonymous

i was stuck..thank u 4 helping... :) !