Question -
Answer -
Given, mass of the car(m) = 1200kg
Initial velocity (u) =90 km/hour = 25 meters/sec
Terminal velocity (v)= 18 km/hour = 5 meters/sec
Time period (t) = 4seconds
Therefore, theacceleration of the car is -5 ms-2.
Initial momentum ofthe car = m ├Ч u = (1200kg) ├Ч (25m/s) = 30,000 kg.m.s-1
Final momentum of thecar = m ├Ч v = (1200kg) ├Ч (5m/s) = 6,000 kg.m.s-1
Therefore, change inmomentum (final momentum тАУ initial momentum) = (6,000 тАУ 30,000) kg.m.s-1
= -24,000 kg.m.s-1
External force applied= mass of car ├Ч acceleration = (1200kg) ├Ч (-5 ms-2) = -6000N
Therefore, themagnitude of force required to slow down the vehicle to 18 km/hour is 6000 N