What is the option?
Air track car A has mass m and velocity v. Air track car B has mass 2m and velocity 3v. The same constant force F is applied to each car until it stops. Car A is brought to rest in time t. The time required to stop car B is:
(A) 2t (B) 3t (C) 6t (D) 9t and (E)18t
Air track car A has mass m and velocity v. Air track car B has mass 2m and velocity 3v. The same constant force F is applied to each car until it stops. Car A is brought to rest in time t. The time required to stop car B is:
(A) 2t (B) 3t (C) 6t (D) 9t and (E)18t
1 Answer
Aug 4, 2018
I get (C)
Explanation:
Car A
It is clear that the force is a retarding force.
Deceleration
#=F/m#
Using the kinematic expression
#v=u+at# .........(1)
we have
#0=v+(-F/m)t#
#=>t=(vm)/F# ......(2)
Car B
Deceleration
#=F/(2m)#
Using (1) we get
#0=3v+(-F/(2m))t_B#
#=>t_B=(3vxx2m)/F#
#=>t_B=(6vm)/F#
Using (2)
#=>t_B=6t#
