Struggling with Physics Word Problems?

[member 392791]

I am in a dilemma right now where I find myself to be very bad at physics. I usually can figure out the concepts, however when it comes to applying these concepts to the word problems, if the problem becomes a little too hard (i.e. not a trivial plug in) I begin to struggle heavily. The worst part is, the tests are not trivial at all and the professor really gives us hard questions. As an example (I'm not looking to get this question answered!) on my test today

A spool of thread consists of a cylinder of radius R1 with end caps of radius R2 as in the end view shown in Figure P10.90. The mass of the spool, including the thread, is m and its moment of inertia about an axis through its center is I. The spool is placed on a rough horizontal surface so that it rolls without slipping when a force T acting to the right is applied to the free end of the thread. Show that the magnitude of the frictional force exerted by the surface on the spool is given by

f = (I + mR1R2/I + mR2^2)T

Determine the direction of the force of friction.

I just completely blanked, and I was like ''how is this testing my understanding of torque..this is a algebra game or something..''

It's just stuff like this that destroys me, what can I do? No matter how many problems I do if I get thrown a curveball I just don't know how to handle it

 

[QuarkCharmer]

Draw a diagram for everything. That word problem is reduced to "plug in numbers" as you put it, given that you can understand what they are describing. The only way to get better at it is to practice. Do a TON of problems. You have already identified what specifically you are having trouble with. Open the book, find those problems, and do them.

 

[HallsofIvy]

You titled this "good at math but bad a physics" so if it were "a algebra game or something" you should be able to do it! The difficulty appears to be precisely that it is "testing your understanding of torque". Draw a picture, as QuarkCharmer suggests, show where the various forces are and use the definition of "torque" to write down algebraic equations that can solve "algebraically".