Engineering mechanics question FORCES

Question

anonymous · Answer

not sure what..... ive been taught about sigma Fx= 0 and sigma Fy=0 so could you uise that to explain?

surry99 · Answer

hint: you need to find the force in the spring at equilibrium (draw a free body diagram) Once you have the force you can use the spring stiffness to determine how much it deflected.  From that you can obtain the unstretched length of the spring.

anonymous · Answer

Deflected?

mathmate · Answer

@dareintheren
Have you done free-body diagrams (FBD) yet?
There are three forces that act on the block.  If you can identify the three forces AND their directions.   Then you use the theorem on forces at a point to say that if the block remains in equilibrium then $\sum$Fx=0 and $\sum Fy=0$. And hence solve for the force in the spring.
By geometry, we know that the stretched length of the spring is 0.5 (=sqrt(0.3^2+0.4^2)).
Using Hookes law and the force on the spring, you can find it's unstretched length.

Key topics to review:
1. Pythagoras Theorem
2. Hooke's law
3. Forces at a point and conditions of equilibrium.
4. Free-body Diagram
5. Resolving forces into two orthogonal components
6. (Optional: triangle of forces)