A particle is projected horizontal with a speed of 20/√3m/s from some height at t=0. at what time will its velocity make 60degree angle with the initial velocity?

1 Answer
Jun 23, 2017

drawndrawn

A particle is projected horizontal and the initial horizontal component of the velocity of the projected particle
V_h =20/sqrt3Vh=203, This will remain unchanged during its flight.

The initial vertical component of the velocity of the projected particle V_v =0Vv=0. This will change with time during its flight by the action of gravitational pull @ g=10m"/"s^2g=10m/s2

Let after tt sec from start the particle's velocity velocity makes angle theta =60^@θ=60with the initial velocity in horizontal direction.
After tt sec from start its vertical component will be

V'_v=V_v+txxg=0+10t=10t" "m"/"s

So (V'_v)/V_h=tantheta

=>(10t)/(20/sqrt3)=tan60^@=sqrt3

=>t=2 sec