There of the fundamental constant of physics are the universal gravitational constant, `G=6.7xx10^(-11) m^(3) kg^(-) s^(-2)`, the speed of light `c=3.0xx10^(8) m//s` and Planck's constant, `h=6.6xx10^(-34) Js^(-1)`. two particles A and V are projected in the vertical plane with same initial velocity `u_(0)` fro part (0,0) and (l,-h) towards each other as shwon in figure
The path of particle A with respect to particle B will be –

Options

A. parabola
B. straight line parallel to x-axis
C. straight line parallel to y-axis
D. None of these.

Answer

B

Explanation

The path of a projectile as observed by other projectile is a straight line.
`v_(A)=ucosthetahati+(usintheta-gt)hatj.V_(AB)==(2ucostheta)hati`
`V_(B)=-ucosthetahati+(usintheta-gt)hatj`
`a_(BA)=g-g=0`
The vertical component `u_(0)sintheta` will get cancelled. The relative velocity will only be horizontal which is equal to `2u_(0)costheta`
Hence, B will travel horizontally towards left w.r.t. A with constant speed `2u_(0)costheta` and minimum distance will be h.