# Homework Help: Basic mechanics problems

1. Apr 15, 2010

### azwraith69

1. The problem statement, all variables and given/known data
attached below..

2. Relevant equations
#1:

#2:$$\Sigma$$Fx = max $$\Sigma$$Fy = may

#3:$$\Sigma$$Fx = 0 $$\Sigma$$Fy = 0

3. The attempt at a solution
#1: none.. don't know what to do yet

#2:
$$\Sigma$$Fx = F1cos30 + F2cos45 - f = max
ax = (F1cos30 + F2cos45 - f) / m = (10cos30 + 14.1cos45 - 10) / 9 = 0.96m/s2

$$\Sigma$$Fy = F1sin30 + F2sin45 = may
ay = (F1sin30 + F2sin45) / m = (10sin30 - 14.1sin45) / 9 = -0.55m/s2

magnitude of a = sqrt(0.962 + (-0.55)2) = 1.1m/s2
direction of a = tan-1 $$\frac{-0.55}{0.96}$$ = -29.8o or 29.8o south of east

#3:
$$\Sigma$$Fx = FMcos33 - FVcos= 0
FVcos$$\theta$$ = FMcos33 = 60cos33 = 50.32N
$$\Sigma$$Fy = -FMsin33 + FVsin$$\theta$$ - w= 0
FVsin$$\theta$$ = 50N + 60sin33 = 82.68N

magnitude of FV = sqrt(50.322 + 82.682) = 96.8N
direction of FV = tan-1$$\frac{82.68}{50.32}$$ = 58.67o

the answers on the book for number 1 are: a)4.2m/s b)29.4 m/s^2 c)4310N

is there anything wrong with numbers 2 and 3??

#### Attached Files:

• ###### problems.doc
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Last edited: Apr 15, 2010