Physics question

I thought the answer would be the horizontal component of the net force acting down the slope, but apparently not. Please explain why this is right or if this is right.

P.S. I know there is a similar question asked here but it relates to the mass of the plane, which is not given here.


The normal reaction is perpendicular to the plane.
Resolve the normal reaction into a horizontal component and a vertical component, equate horizontal and vertical forces and use the resulting equations to eliminate the normal reaction.

  • $\begingroup$ But the force required to balance it is only horizontal so how can I balance a normal force in both the x and y planes with a force in only the x plane? $\endgroup$ – Varun Jahagirdar Jun 5 '18 at 8:28
  • $\begingroup$ @VarunJahagirdar The normal has a horizontal and vertical component. One “balances” the weight and the other the applied force. $\endgroup$ – Farcher Jun 5 '18 at 8:34

Try setting up a coordinate system along the hypotenuse and perpendicular to it. Then resolve the forces in those two axes. Finally equate the forces along the hypotenuse to achieve equilibrium. You will get your answer after that.

  • $\begingroup$ I think I tried to do what you are suggesting but it gave me the wrong answer. I'm not entirely sure what you are trying to say $\endgroup$ – Varun Jahagirdar Jun 5 '18 at 8:31
  • $\begingroup$ I am saying draw a perpendicular to the hypotenuse. Take it as (say) Y axis and then take the hypotenuse itself as X axis. So now you have a new coordinate system. After this resolve the Horizontal applied force along these new X and Y coordinates. Then take the Gravitational force, F=m*g and resolve it along the X and Y axes. Then equate the various forces along X axis to get the answer. (Be aware to mark the angles APPROPRIATELY while resolving the applied horizontal force and the gravitational force, which is why you are getting a wrong answer. ) $\endgroup$ – Global Jun 5 '18 at 8:47

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