Ahot rod can accelerate from 0 to 60 km/h in 5.4 s.
(a) what is its average acceleration, in m/s2, during this time?
(b) how far will it travel during the 5.4 s, assuming its acceleration is constant?
(c) from rest, how much time would it require to go a distance of 0.25 km if its acceleration could be maintained at the value in (a)?

Explanation:

a) We have equation of motion v = u + at

      Initial velocity, u = 0 km/hr = 0 m/s

      Final velocity, v = 60 km/hr = 16.67 m/s  

      Time, t = 5.4 s

      Substituting

                       v = u + at  

                       16.67 = 0 + a x 5.4

                       a = 3.09 m/s²

      Acceleration is 3.09 m/s²

b) We have equation of motion s = ut + 0.5 at²

         Initial velocity, u = 0 m/s

         Acceleration, a = 3.09 m/s²

         Time, t = 5.4 s      

      Substituting

                       s = ut + 0.5 at²

                       s = 0 x 5.4 + 0.5 x 3.09 x 5.4²

                       s = 45.05 m

       Distance traveled is 45.05 m

c) We have equation of motion s = ut + 0.5 at²

         Initial velocity, u = 0 m/s

         Acceleration, a = 3.09 m/s²

         Displacement, s = 0.25 km = 250 m      

      Substituting

                       s = ut + 0.5 at²

                       250 = 0 x t + 0.5 x 3.09 xt²

                       t = 12.72 s

       Time taken to travel 250 m is 12.72 s

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