You build a shelf by putting a 0.90 m board across two supports. One support is at the left end of the board and the other is 0.10 m from the right end. The board has a mass of 1.25 kg and you place a potted plant with a mass of 3.40 kg, 0.65 m from the left end of the board.

B4

To get up on the roof, a person (mass 87.0 kg) places a 5.60 m aluminum ladder (mass 14.0 kg) against the house on a concrete pad with the base of the ladder 2.00 m from the house. The ladder rests against a plastic rain gutter, which we can assume to be frictionless. The center of mass of the ladder is 2 m from the bottom. The person is standing 3 m from the bottom. What are the magnitudes (in N) of the forces on the ladder at the top and bottom? top N bottom N

A horizontal 8 kg plank is 3.0 m in length and has its center of mass at the geometrical center. A 2 kg mass is placed 1.0 m from one end and the plank is supported from the ends. Calculate the forces of support. 1.0 m 2 kg 3.0 m

Bob and Anna sit on opposite ends of a uniform see-saw which is 12.0 m in length. The see-saw is balanced by a fulcrum which is located 4.00 m from Bob. Bob has a mass of 85.0 kg, and the see-saw itself has a mass of 100 kg. Anna’s mass is unknown. NOTE THAT THE FULCRUM IS NOT PLACED AT THE CENTER OF MASS OF THE SEE- SAW!!! a)   What is the net torque on the see-saw? Explain clearly and briefly how you know. b) Draw a properly labeled extended force diagram of the see-saw   c) Solve for Anna’s mass. Show your work clearly!

A 100-N board 12-m long, rests on two supports, one support is 1m from the end and other is 3 m from the end of the board. A 400-N block is placed on the board 3 m from one end. Find the force exerted by each support on the board.

Bob and Anna sit on opposite ends of a uniform see-saw which is 12.0 m in length. The see-saw is balanced by a fulcrum which is located 4.00 m from Bob. Bob has a mass of 85.0 kg, and the see-saw itself has a mass of 100 kg. Anna’s mass is unknown. NOTE THAT THE FULCRUM IS NOT PLACED AT THE CENTER OF MASS OF THE SEESAW!!!   a) What is the net torque on the see-saw? Explain clearly and briefly how you know.   b) Draw a properly labeled extended force diagram of the see-saw.   c) Solve for Anna’s mass.

A seesaw is a flat board that is balanced on a fulcrum (point of balance). When the weight at either end is equal, the seesaw is balanced and both ends are at the same height. When weight is added to either side, the balance will tilt in that direction. To prevent the balance from tipping, the location of the fulcrum must be moved to accommodate the difference in weights placed on each end. A playground equipment company wants to produce a seesaw that will be perfectly balanced when an adult and a child are on either end. The company estimates that an adult, on average, weighs four times as much as a child. The length of the seesaw is 10 feet. C A { 01 2 3 4 5 6 7 8 9 10