Solve Physics Homework: Forces & Friction | Get Expert Help

[koralex90]

I am having trouble solving this for my physics homework. Please help with these two problems!

http://img151.imageshack.us/img151/5049/scan1wd3.jpg

I just don't know where to start... please guide me..

 

[OlderDan]

For #7, draw the string attached to the hook using the angles given. Assume the picture hangs evenly and the strings are attached to the picture symmetrically so each end of the string supports the same weight (this is implied by the stated angles). The weight of the picture is supprted by the vertical components of the tensions. The horizontal components of the tension pull inward on the edges of the picture.

For #8 draw a free body diagram for each mass. Since the pulley has no mass, the tension in the string is uniform. Each mass will move the same distance with the same speed and the same magnitude of acceleration. You should be able to write two equations involving the unknown tension and the unknown acceleration, and solve them simultaneously for both variables.

 

[kyle8921]

Sure, I would be happy to help you with your physics homework. Let's take a look at the two problems you have provided. The first problem asks you to calculate the net force on the block. To do this, we need to first identify all of the forces acting on the block. From the diagram, we can see that there is a force of 50 N pushing the block to the right, a force of 30 N pushing the block to the left, and a force of 10 N pushing the block downward. To find the net force, we need to add up all of these forces. However, we also need to take into account the direction of each force. Since the force of 30 N is opposite in direction to the force of 50 N, we need to subtract 30 N from 50 N. This gives us a net force of 20 N to the right. We also need to add the downward force of 10 N, giving us a final net force of 20 N to the right and 10 N downward.

For the second problem, we are asked to calculate the coefficient of friction between the block and the surface. To do this, we need to use the formula for friction: Ff = μN, where Ff is the force of friction, μ is the coefficient of friction, and N is the normal force (the force perpendicular to the surface). We can see from the diagram that the normal force is equal to the weight of the block, which is given to us as 20 N. We also know that the force of friction is equal to the net force acting on the block, which we calculated in the first problem as 20 N to the right and 10 N downward. Plugging these values into the formula, we get 20 N = μ(20 N), which simplifies to μ = 1. This means that the coefficient of friction between the block and the surface is 1.

I hope this helps guide you in solving these problems. Remember to always identify all of the forces acting on an object and take into account their direction when calculating net force. Also, for friction problems, use the formula Ff = μN and remember that the normal force is equal to the weight of the object. Good luck with your homework!