**Solution: **In 60 minutes, the minute hand of a watch completes one revolution. Therefore,

in 40 minutes, the minute hand turns through 2/3 of a revolution. Therefore,

θ = 2 × 360°/3

or 4π/3

radian. Hence, the required distance travelled is given by

l = r θ = 1.5 × 4π/3 cm = 2π cm = 2 × 3.14 cm = 6.28 cm.