Hi,
For Q1, the following facts are important and should be
memorised:
Velocity v = ds/dt,
Acceleration a = dv/dt,
Displacement = integral of v with respect to t,
Velocity = integral of a with respect to t.
In (a), consider t = 0.
In (c), what is v when the particle is momentarily at
rest.
For Q2, we are given that
V is an expression involving h,
dh/dt = 1/2,
h = 6
and we want to find dV/dt.
Applying the chain rule, we have dV/dt = (dh/dt) (dV/dh),
where the value of dV/dh can be found with h = 6.
Try it, thanks!
Cheers,
Wen Shih