A 60 kg girl on a swing is pulled 1.5 meters back and then released. The girl oscillates at pi/3 radians per second. How far from equilibrium will the girl be in 4 seconds into the motion

-0.75 m

Explanation:

The displacement of the girl is given by x = x₀cosωt where x₀ = maximum displacement of swing = 1.5 m, ω = angular frequency = π/3 rad/s and t = time of swing = 4 s

Substituting the values of the variables into the equation, we have

x = x₀cosωt

x = (1.5 m)cos(π/3 rad/s × 4 s)

x = (1.5 m)cos(2π/3)

x = (1.5 m)cos120°

x = 1.5 m × -0.5

x = -0.75 m

So, the girl is 0.75 m to the left of the equilibrium position 4 seconds into the motion.