Question

A projectile is projected at an angle ø(>45^o ) with an initial velocity u. the time t at which its horizontal component will equal the vertical component in magnitude is:-

a) t=u/g(cosø-sinø).     b) t=u/g(cosø+sinø).      

c)  t=u/g(sinø-cosø).    d) t=u/g(sin²ø-cos²ø).

Answer 1

Correct answer is (c)

Explanation:

Let the angle be ø,

Aat any time t,

in the x-direction.

Vx = ucos(ø)

in y-direction.

Vy = usinø – gt

Now Vx = Vy (given)

usinø – gt = ucosø

u(sinø – cosø) = gt

t = [u(sinø – cosø)]/g