Presentation on theme: "Static Equilibrium KEY. 1.How many different positions of stable equilibrium and unstable equilibrium are there for a cube (consider each surface, edge."— Presentation transcript:
Static Equilibrium KEY
1.How many different positions of stable equilibrium and unstable equilibrium are there for a cube (consider each surface, edge and corner to be a different position)? Stable: flat sides = 6 Unstable: Corners + sides = 8 + 12 = 20
2. A window washer is standing on a scaffold supported by a vertical rope at each end. The scaffold eights 200 N and is 3.00 m long. What is the tension in each rope when the 700 N worker stands 1.00 m from one end? T1T1 T2T2 200N700N Sum torques around T1: Sum torques around T2:
3. A student hangs a 25g mass from the 0.0 m mark on a meterstick and another at the 20. cm point. How large of a mass should the student hang at the 85 cm point if the student wants to perfectly balance the meterstick on her finger placed at the 50. cm mark? m = ? 0.025kg 0 20 50 85 Sum torques around 50cm mark:
4. A 245 N shop sign is hung from the end of a 1.70 m, 155 N beam. The beam is placed flat against the wall. 1.35 m from the wall, a cable is attached, one end to the beam and the other end to the wall. What is the tension in the wire if the wire makes a 35 o angle with the beam? T 35 o Tsin35 o 155N245N 0.85m 1.35m 1.7m Sum torques around the wall because I don’t know the frictional force provided by the wall.
5. A 50.0 kg porch swing is 2.00 m long and is supported by two cables vertically connecting each side of the swing to the ceiling of the porch. If a 35 kg kid is sitting 0.35 m from the right end of the swing and a 45 kg kid is sitting 0.45 m from the left end, what is the tension in each support cable? 50.0kg(9.8m/s 2 ) 45kg(9.8m/s 2 )35kg(9.8m/s 2 ) 0.45m 1.00m0.35m T1T1 T2T2