Question

a motor car of mass 1000 kg is moving along a straight line with a uniform velocity of 90 kilometre per
hour if velocity slowdown waiting kilometre per hour in 4 seconds by an unbalanced external calculate the acceleration and change in momentum also calculate the magnitude of force required

Answer 1

initial velocity = 90km/h = 90 ×5/18 m/s = 25m/s 

 final velocity = 18 km/h = 18× 5/18 m/s = 5 m/s 

 

acceleration = (final velocity -initial velocity )/ time taken

                     =( 25 - 5)/4 = 5 m/s²

now,

change in momentum = m( final velocity - initial velocity )

                                      =1200 ×( 25 - 5) = 24000 Kgm/s 

force = change in momentum / time

         = 24000/4 = 6000 N  

Answer 2

solution is attached above ...