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

grav forces affect all objects magnetic forces affect magnetic objects and electric currents

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day