A2.00-kg, frictionless block is attached to an ideal spring with force constant 300 n/m. at t=0 the block has velocity -4.00 m/s and displacement +0.200 m.
find:
(a) the amplitude and (b) the phase angle.
c) write an equation for the position as a function of time.
assume x(t) in meters and t in seconds

Ahuge (essentially infinite) horizontal nonconducting sheet 10.0 cm thick has charge uniformly spread over both faces. the upper face carries +95.0 nc/m2 while the lower face carries -25.0 nc/ m2. what is the magnitude of the electric field at a point within the sheet 2.00 cm below the upper face? (ε0 = 8.85 × 10-12 c2/n · m2)