Rubric6A

# Rubric6A - 7B-A/B Spr 08 DL Sec Quiz 6 Last 6 digit of...

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| F grav | = mg, g = 10 m/s^2 Σ F = m a | τ | = F _ r = (F tangential )r ΣτΔ t = Δ L 7B-A/B Spr 08 Quiz 6 DL Sec Grading: Last 6 digit of student ID: Name: First three letters of your family name 1. A 60 kg mass is placed 1 m from the left end of a 1.5 meter-long board as shown from the side. The board is very light and you may ignore its mass. One end of the board is attached to the left wall while the other is held up by a rope forming a 45 degree angle. The entire system is stationary. Draw an extended force diagram showing all external forces on the board & mass system (treat them as a single object). Calculate numerically the horizontal and vertical components of all of the forces and make sure to scale your forces properly. Make sure to show your work and to label your diagram carefully. Choose the pivot point to be at the left end of the board (no torque due to F Wall on board&mass !). You can choose your pivot point to be anywhere you like, but choose one that will make your life easier. Then, torque exerted by F Earth on board&mass and vertical component of F rope on board&mass on board&mass must cancel, i.e., τ = τ Due to the force of Earth on board&mass + τ Due to the force of rope on board&mass = 0 Define direction (into the paper) to be positive τ = + (1m)F Earth on board&mass – (1.5m)F y, rope on board&mass = 0 F y,rope on board&mass = (1m)F Earth on board&mass / (1.5m) = 600Nm/1.5 m= 400N Since the angle of the rope to horizontal is 45º, F x,rope on board&mass = 400N as well.

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## This note was uploaded on 10/26/2008 for the course PHY 7b taught by Professor Taylor during the Spring '08 term at UC Davis.

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Rubric6A - 7B-A/B Spr 08 DL Sec Quiz 6 Last 6 digit of...

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