Can some one solve this physics problem with calculations please?

Question

a body is moving in a straight line at a velocity of 54km/h undergoes an accelaration of 3m/s.find the velocity after 2s

Answer 1

v = u + at

v = 15 + 3*2

v = 21 m/s

because 54km/h = 15m/s

Answer 2

v = 54 km/h = 15 m/s

because 54km = 54000 m

and 1 hour = 3600 seconds

54000/3600 = 15

Use this formula: v = v0 + at

v = 15 + 3(2)

v = 21 m/s

21/1000 = .021

.021(3600) = 75.6 km/h

Answer 3

Acceleration is not measured in meters per second, but in m / sec^2.

Or meters per sec per sec. So assume the car undergoes an acceleration of 3 m. sec^-2.

Then the increase in V = 3 X 2 m /sec

                                  = 6 m/sec

                                  = 6 X 3600 m /h

                                  = 21 600    m / h

                                  = 21,6 km/h

Therefore new speed of car = 21,6 + 54 km/h

                                       =  75,6 km/h

Answer 4

all you need to do is convert your units...

54km = 54000 m

1h =  3600 s

54km/h = 15m/s

+3m/s = 18m/s or 64.8 km/h

Answer 5

v(t) = at + v0

a = 3 m/s²

v0 = 54 km/s = 54,000/3,600 m/s = 15 m/s

t = 2 s

v(2) =  3*2 + 15 = 21 m/s