4 Newton Problems

For all of these four problems, break them down to a FBD with x and y axes and set your positive axes.

Equilibrium:
This is when the object isn't moving and all the forces are equal to each other. The object is usually hanged up by two strings or beams. Using trig will find the unknown angle or side, depending on which is given.

Inclines:
This is where you have a slanted surface and an object at the top of that surface. There is a friction force acting on the object as it slides down the slanted surface. the equation for friction is mu*fn. The FBD has to be shifted a bit in terms of x and y.

Pulleys:
There are 2 FBDs for these types of problems, one for each object on the 2 ends of the pulley. We assume there's no friction and tension is the same for both sides.

Trains:
These are similar to pulleys. You still need 2 or more FBDs, depending on how many cars you have on the train. When your trying to find the acceleration, draw a FBD of the whole system. Friction is included in this problem. To solve for tension, you have to find each individual tension between each 2 cars.