Physics Help Forum Newton's Laws Test Problem

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Oct 29th 2018, 02:33 PM #1 Junior Member   Join Date: Oct 2018 Location: Baltimore, MD Posts: 2 Not sure what happened to my post, it kind of vanished after editing. Basically, I have this problem (image attached) and I'm stuck. I have these 2 equations but I have 3 unknowns (normal force, acceleration in x, and angle theta). If anyone could toss me in the right direction I would greatly appreciate it. Thanks! The image is quite large, so sorry about that!
 Oct 30th 2018, 02:35 AM #2 Senior Member     Join Date: Jun 2016 Location: England Posts: 844 My current computer setup will not allow me to view the posted image, however the brief description you give sounds very much like a basic trigonometry problem. The Force in X is related to the Normal force via the angle Theta XForce = NForce * SIN(Theta) __________________ ~\o/~
 Oct 30th 2018, 11:06 AM #3 Physics Team     Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,339 You're not too far away from being able to answer (2). You have figured out that F_y = 0, you have an expression for F_n, and you almost have F_x (you actually have written acceleration in the x-direction; the force F_x is acceleration times mass). So - first off, what's the total force, F_net? You could use |F_net| = sqrt(|F_x|^2 +|F_y|^2), but given that F_y=0 it should be pretty obvious what F_net is. Then, use simple trig to determine the angle theta if |F_n|/|F_net| = 0.554

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