physics question

Question

A freight train has a mass of 1.3 × 107 kg.

If the locomotive can exert a constant pull of 6.6 × 105 N, how long would it take to increase the speed of the train from rest to

78.2 km/h? Disregard friction.

Answer 1

F = ma = m (v₂ - v₁) / Δt

You want to find Δt.

Δt = m (v₂ - v₁) / F

You know the following:

m = 1.3 x 10⁷ kg

F = 6.6 x 10⁵ N

v₂ = 78.2 km/h (convert this to m/s)

v₁ = 0 (started from rest)

Plug in the numbers (with v₂ in m/s) and get Δt in seconds.