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Homework Statement
An electric motor is used to pull a 125kg box across a floor using a long cable. The tension in the cable is 350N and the box accelerates at 1.2 m/s/s [fwd] for 5.0s. The cable breaks and the box slows down and stops
a )Calculate the coefficient of kinetic friction. [ans:0.16]
b) How far does the box travel up to the moment the cable breaks? [ans: 15m]
c) How far does the box travel from the moment the cable breaks until it stops? [ans: 11m]
Homework Equations
Kinematics equations
The Attempt at a Solution
Ft-Fk=ma
350-Fk=(125)(1.2)
Fk=200N
μk=Fk/Fn
=200/(125)(9.8)
μk=0.16
b) D=Vft-1/2at^2
= 0-1/2(-1.2)(5)^2
= 15m
c)
I know my solution for b) is correct. But I don't understand why the Vf is zero when the cable breaks because shouldn't the Vf be zero when the box actually comes to a stop and not when the cable breaks. Assuming I solved b) correct, and Vf = 0 then how would I solve c) when the box actually comes to a stop?