Q: What is torque? A: Torque is a physical vector quantity characteristic for an object in rotational motion around a certain given axis. By definition torque () is the cross product between the vector of position (r) of the point where a force is applied ( from an origin considered to be on the axis of rotation) and the applied force (F) ( = r x F). According to the definition of the cross (or vector) product, the magnitude of the torque is equal to the magnitude of r times the magnitude of F multiplied by sine of the angle () between r and F ( = r F sin ). In this expression for magnitude of the torque, the product (r sin ) is equal to the magnitude of the distance (d) between the axis of rotation and the "line of action" of the force (F) (r sin = d). This distance (d) is called "arm of the force." Now, the torque can be expressed as = Fd (torque is equal to force multiplied by the arm of the force.) Intuitively, torque can be interpreted as "force with a twist" since it results in rotation of the object on which the force is applied. 
Q: An electric motor runs at 1000 rpm and delivers 3.0 hp. How much torque does it deliver? A: To
solve this problem we need to convert to SI units. 
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Torque as a Vector 

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