If at an instant the velocity of a projectile be 60 m/s and its inclination to the horizontal be 30 degree ,

Question

If at an instant the velocity of a projectile be 60 m/s and its inclination to the horizontal be 30^o , at what time interval (in sec ) after that instant will the particle be moving at right angles to its former direction. (g=10 m/s²) .

Answer 1

Please see here is the general formula derivation for your question.

You simply put the values and get the required answer