- #1
dougiehazard
- 2
- 0
- Homework Statement
- Balance the following face plate if the masses are as follows:A = 2.8 kg, B = 3.5 kg, C = 4.2 kg, D = 4.8 kg, E = ?(What angle and mass should E be placed to balance the other 4 masses
Balance the forces east-west:
3.5kg*sin45º + 4.2kg*cos30º - 4.8kg*sin30º - E*cosΘ = 0
E*cosΘ = 3.712 kg
balance north-south:
2.8kg + 3.5kg*cos45º - 4.2kg*sin30º - 4.8kg*cos30º + E*sinΘ = 0
E*sinΘ = 0.982
EsinΘ / EcosΘ = 0.982 / 3.712
tanΘ = 0.2645
Θ = 14.8º ◄
E = 3.712kg / cos14.8º = 3.84 kg ◄
If that's not right, then you want to balance the moments.
balancing east west:
3.5kg*0.35*sin45º + 4.2kg*0.315*cos30º - 4.8kg*0.6*sin30º - E*0.2*cosΘ = 0
E*cosΘ = 2.86 kg
and north-south
2.8kg*0.35 + 3.5kg*0.35*cos45º - 4.2kg*0.315*sin30º - 4.8kg*0.6*cos30º + E*0.2*sinΘ = 0
E*sinΘ = 6.55 kg
EsinΘ / EcosΘ = 6.55 / 2.86
tanΘ = 1.706
Θ = 59.6º ≈ 60º
E = 6.55kg / sin59.6º = 7.6 kg
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