Question

A missile is launched from the earth surface with the initial velocity of 100ms-1. at an elevation of 30 degree.calculate

2. greatest height attained.

2. time of fright.

3. Velocity of a missile at time 8 second

Answer 1

1.

$$H_{\max}=\frac{v_0^2\sin^2\theta}{2g}$$ $$H_{\max}=\frac{100^2\sin^230^\circ}{2*9.8}=128\:\rm m$$

2.

$$t=\frac{2v_0\sin\theta}{g}$$ $$t=\frac{2*100\sin30^\circ}{9.8}=10.2\:\rm s$$

3.

$$v=\sqrt{(v_0\cos\theta)^2+(v_0\sin\theta-gt)^2}$$ $$v=\sqrt{(100\cos30^\circ)^2+(100\sin30^\circ-9.8*8.0)^2}=91\:\rm m/s$$