Cartesian coordinates and torque

AI Thread Summary
The discussion centers on calculating the torque τ_B due to a force F about point B, located at Cartesian coordinates (0, b). The correct expression for torque involves the distance from point B to the point of force application and the perpendicular component of the force. The user initially attempted to use F*b*sin(pi-(theta)), which was incorrect, leading to confusion about the appropriate trigonometric function to use for finding the perpendicular component. The correct approach requires understanding the geometry of the situation and applying the right trigonometric relationships to determine the torque accurately. Clarification on these concepts is essential for solving the problem effectively.
RhysticGenesis
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This section I don't understand at all... but the problem is What is the torque tau_B due to force F_vec about the point B? (B is the point at Cartesian coordinates (0, b), located a distance b from the origin along the y axis.)
Express the torque about point B in terms of F, theta, phi, pi, and/or other given coordinate data. an image can be found at
http://session.masteringphysics.com/problemAsset/1011042/19/MRB_rk_0.jpg

I put in F*b*sin(pi-(theta)) it noted that I was wrong... I don't understand? and that's just hte beginning of my problems in this section :cry:
 
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The torque "due to force F around point B" is the product the distance from B to the point at which F is applied and the component of F perpendicular to the line from B to the point where F is applied.
 
so b*F*tan(pi-(theta)) ? I still don't understand I know if I do sin(pi-(theta)) Its opp over hyp so it would be parallel to b but I am not sure what trig woudl get it to go perp then
 
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