A projectile is thrown with a velocity of 39.2 m/s on the upward direction making an angle of `60^@` with horizontal . Find time after which the inclination is `40^@` with horizontal.

Explanation

Let the required time be t,
`S= ut + 1/2 at^2`
`39.2 = 29.4 xx t- 1/2 xx 9.8 t^2`
`4.9 t^2- 29.4t +39.2= 0` solve for t.