A 2000 kg car traveling to the east is slowed down uniformly from an intitial velocity of 40.0 m/s by a 7000 N braking force acting opposite the car's motion. using the impulse momentum theorem, what is the car's velocity after 3.0 seconds?
1 Answer
May 25, 2018
From The impulse-momentum theorem we know that the change in momentum of an object equals the impulse applied to it.
#sf vecJ = Deltasfvecp#
If mass of the object is constant we have
#vecsfFDeltasft = mΔsfvec v#
Given force is braking force. Inserting given values we get
#-7000xx3.0 = 2000xxΔsfvec v#
#=>Δsfvec v=-21000/2000=-10.5\ ms^-1#
Now
#Δsfvec v=sfvec v_"final"-sfvec v_"initial"#
#=>-10.5=sfvec v_"final"-40#
#=>sfvec v_"final"=40-10.5=29.5\ ms^-1#
