Question

2 racing cars acquire velocities 18kmph and 36kmph in 0.5 sec if they are accelerated uniformly from rest find their accelarations

Answer 1

For first car,

Initial velocity ( u ) = 0.

Final velocity ( v ) = 18 km/h   = 5 m/s.

Time ( t ) = 0.5 sec

Acceleration ( a ) = ( v - u ) / t

                            = ( 5 m/s - o ) / 0.5 s

                            = 5 m/s / 0.5 s

                            = 5 * 10 m / 5 s ^ 2

                           = 10 m / s ^ 2 = 10 m s ^ -2.

For second car,

Initial velocity ( u ) = o.

Final velocity ( v ) = 36 km/h = 10 m/s.

Time ( t ) = 0.5 s

Acceleration ( a ) = ( v - u ) / t

                           = ( 10 m/s - o ) / 0.5 s

                           = 10 m * 10 / 5 s ^ 2

                          = 20 m/s ^ 2  = 20 ms^ -2.