Question

a 1.5-kilogram cart initially moves at 2.0 meters per second. it is brought to rest by a constant net force in 0.30 second. what is the magnitude of the net force

Answer 1

Since acceleration is constant, we can use kinematic equation v=u+at( v= final velocity = 0...since finally cart stops. u = initial velocity = 2m/s, a = deacceleration and t= 0.3 sec). Therefore 0 = 2 - a(0.3). a = 20/3 = 6.67m/s^2. Net force = massxacceleration = 1.5x6.67 = 10N.