A train of mass 50000 kg starts from rest and moves with uniform acceleration 5 km/h2 then, find its kinetic energy after 30 minutes.

12 kJ

Explanation:

Given:

v₀ = 0 km/h

a = 5 km/h²

t = 30 min = 0.5 h

Find: v

v = at + v₀

v = (5 km/h²) (0.5 h) + 0 km/h

v = 2.5 km/h

v = 2.5 km/h × (1000 m/km) × (1 h / 3600 s)

v = 0.694 m/s

KE = ½ mv²

KE = ½ (50,000 kg) (0.694 m/s)²

KE = 12,000 J

KE = 12 kJ

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