A freight train has a mass of 1.1 ✕ 107 kg. If the locomotive can exert a constant pull of 8.1 ✕ 105 N, how long does it take to increase the speed of the train from rest to 60 km/h?

226.45 s.

Explanation:

Using Newton's fundamental equation,

F = ma ... Equation 1

Where F = force, m = mass of the freight train, a = acceleration of the freight train.

make a the subject of the equation,

a = F/m ... Equation 2

Given: F = 8.1*10⁵ N, m = 1.1*10⁷ kg

Substitute into equation 2

a = 8.1*10⁵/1.1*10⁷

a = 0.0736 m/s²

Using

a = (v-u) / t ... Equation 3

make t the subject of the equation

t = (v-u) / a ... Equation 4

Given: v = 60 km/h = 60 (1000/3600) = 16.67 m/s, u = 0 m/s (from rest), a = 0.0736 m/s²

Substitute into equation 4

t = (16.67-0) / 0.0736

t = 16.67/0.0736

t = 226.45 s.