A body is projected with an initial speed of `100sqrt3ms^(-1)` at an angle of `60^(@)` above the horizontal. If `g=10ms^(-2)` then velocity of the projectile
a) is perpendicular to it’s acceleration at the instant `t=15 sec`.
b) Is perpendicular to initial velocity of projection at `t=20 sec.`
c) Is minimum at the highest point
d) Changes both in magnitude and direction, during its flight.

Options

A. a, b, c and d are corect
B. only a, c and d are correct
C. only b, c and d are correct
D. only a,b and d are correct

Answer

A