# Negative torque and negative velocity during reverse dynamics in Matlab Robotics Toolox.

I'm using Robotics Toolox Matlab and I did Reverse dynamics using code below.

[qreach,err] =  rob.ikcon(T1, qready);
%compute inverse dynamics using recursive Newton-Euler algorithm
tauf = rne(rob, q, qd, qdd);


And when I plotted angular velocity and torque it shows some negative values as shown in Fig. I want to know why so and what is the physical significance of negative veloity and torque in robotics. Thanks.