Question

two particles are fired from the same point with speeds 100 m/ s and 100 m/s .firing angles with horizontal are 60 degree and 120 degree.the time after which their velocity vector become perpendicular to each other is

Answer 1

here is the first part, you just take dot product and set it to zero to get time. For some reason I can't upload the next part, so you have to take the dot product on your own.