Question

a projectile is projected with a speed of 30 m/s at angle 30 with vert.speed of proj. when its dirn of motn makes sn anhle 30 with horizontal.

Answer 1

I guessed, your question is -----> A projectile is projected with speed of 30 m/s at an angle 30° with vertical then, find the speed of projectile when its make an angle 30° with horizontal.

projectile makes an angle 30° with vertical it means , it also makes 60° angle with horizontal.

Let speed of projectile at that position where it makes 30° angle with horizontal.

we know, horizontal component of projectile doesn't change.

so, initial horizontal component of projectile = final horizontal component of projectile

or, ucos60° = vcos30°

or, 30cos60° = vcos30° [ given, u = 30m/s ]

or, 30 × 1/2 = v × √3/2

or, v = 10√3 m/s

hence, answer is 10√3 m/s