Question

A ball is projected from a point $O$ as shown in figure. It will strike the ground after $(g=10m/s^2$ )

• A. 4 s
• B. 3 s
• C. 2 s
• D. 5 s

Answer 1

Answer: (A)

$s_y=u_{x}T+\frac{1}{2}{a}_y{T}^2$
$-60=10\sin 30^{\circ }\cdot T-\frac{1}{2}g{T}^2$
$-60=5T-5T^2$
$T^2-T-2=0$
$T=4s$