Transverse waves on a string have wave speed 12.0 m/s, amplitude 0.05 m and wavelength 0.4 m. The waves travel in the +x-direction and at t=0 the x=0 end of the string has zero displacement and is moving upwards.
(1) Write a wave function describing the wave.
(2) Find the transverse displacement of a point at x=0.25 m at time t=0.15 s.
(3) How much time must elapse from the instant in part (b) until the point at x=0.25 m has zero displacement?