Question

A car is accelerated uniformly from 54 km per hour to 72 km per hour in 3sec. calculate (a) the acceleration of car (b)the distance covered by the car in that time

Answer 1

Acceleration = Change in velocity / Time
                     = v - u / t
72km/h = 72 × 5 / 18 m/s = 20m/s
54km/h = 54 × 5 / 18m/s  = 15m/s
     Acceleration = 20-15 / 10 
                           = 5 /10 
                           = 0.5 m/s²
To find distance we use the formula 
              v² = u² + 2aS   here v is the final velocitiy (72km/h)
                                              u is the initial velocity(54km/h)
                                               a is the acceleration
                                              S is the distance
             20² = 15² + 2 × 0.5 × S 
             400 = 225 + 1×S
             400 - 225 = S
           S = 175 m
Therefore distance = 175m