A body oscillates with SHM according to the equation (in SI units), x = 10 cos[4πt + π/2]. At t = 0.5 s, calculate the (a) Displacement (b) Speed (c) Acceleration of the body.
In simple harmonic motion (SHM), the displacement x(t) of a particle from its equilibrium position is given by:
x(t) = A cos(ωt + φ)
where A is the amplitude of the displacement, (ωt + φ) is the phase of the motion, and φ is the phase constant.
Given: A = 10, ω = 4π, φ = π/2
Time period T = 2π/ω = 2π/4π = 0.5 s
At t = 0.5 s:
(a) Displacement = 10 cos[4π(0.5) + π/2] = 10 cos[2π + π/2] = 0 m
(b) Speed = -ωA sin(ωt + φ) = -(4π)(10) sin(2π + π/2) = -40π m/s
(c) Acceleration a(t) = -ω2A cos(ωt + φ) = -ω2x(t)
∴ a(t) = -(4π)2(10) cos(2π + π/2) = 0 m/s2