**1. A particle is projected with an initial velocity of V m/s and attains a maximum height of 12.5m before landing 100m from the point of projection. Calculate the value of V. ** use these three equations, all derived from the basic equations for kinematics w/ constant acceleration. then ...
Can someone check my answer for this?

**2. The displacement, x, of a particle moving in a straight line is represented by the equation: x = 5cos4t**

Find a) The initial velocity of the particle

b) initial acceleration of the particle
a)

initial velocity.. when t = 0, v = 0

b)

when t =0, a = -80

both correct