A shell is fired from a fixed artillery gun with an initial speed u such that it hits the target on the…

A shell is fired from a fixed artillery gun with an initial speed u such that it hits the target on the ground at a distance R from it. If t1 and t2 are the values of the time taken by it to hit the target in two possible ways, the product t1t2 is:
  1. R/2g
  2. R/g
  3. 2R/g
  4. R/4g

Solution

We know for complementary angle range is same for same projection speed.
t1=2usin(θ)g ….. (i)
t2=2usin(90-θ)g ….. (ii)
R=2u2sinθcosθg .… (iii)
From equation (i) and (ii)
t1t2=4U2sinθcosθg2
(Using the value of R from equation iii)
t1t2=2Rg

Asked in: JEE Main 2019 (12 Apr Shift 1)

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