The horizontal and vertical displacements of a projectile at time t are `x = 36t and y = 48t -4.9t^2` respectively. lmtial velocity of the projectile in `ms^-1` is

Options

A. 15
B. 30
C. 45
D. 60

Explanation

Comparing`h=Ax-Bx^2`with standrad equation of trajectory,
`h=xtantheta-(gx^2)/(2u^2cos^2theta)` then,
`impliesA=tantheta=tan45^0=1`
`B=g/(2u^2cos^2theta)=10/(2xx20^2xxcos^2 45^(@))=0.025`
`A/B=1/0.025= 40/1`
`A:B=40:1`