- #1
StephenPrivitera
- 363
- 0
A uniform solid disk of mass M and radius R hangs from a string of length l attached to a smooth wall. We want the tension in the string and the normal force exerted by the wall.
|
|\ <--- I call this angle A
|_\
|__\
|_(..) <--- that's a disk
|
|
So I have it set up so the tension points up and to the left, the normal exactly to the right and the weight exactly down. The answer appears to take the normal perpendicular to the tension, which quite confuses me. Anyway, I get
TsinA=N
TcosA=Mg
so N=MgtanA
and T=Mg/cosA
The book gets T=MgcosA
and N=MgsinA
|
|\ <--- I call this angle A
|_\
|__\
|_(..) <--- that's a disk
|
|
So I have it set up so the tension points up and to the left, the normal exactly to the right and the weight exactly down. The answer appears to take the normal perpendicular to the tension, which quite confuses me. Anyway, I get
TsinA=N
TcosA=Mg
so N=MgtanA
and T=Mg/cosA
The book gets T=MgcosA
and N=MgsinA