Question

Force diagram worksheet 1 Draw the scene. Circle the item that is being analyzed. Draw the FBD. Sum the moments and solve for the forces. Assume all beams are of even weight distribution, ie a 5 m beam that weighs 50 N weights 10N per meter. O 5. You are holding a rope that goes over a pulley and then wraps around pulleys per the diagram. Can you pull with enough force to lift the platform that you are standing on? How much do you weigh and how much do you need to pull? o o 6. You are using a 3 m lever to lift a 800 N boulder. You need to lift the boulder 10 cm. You can exert 400 N down. Where do you place the fulcrum or pivot point to barely lift the boulder? What is the upward force of the pivot on the lever? If you can move your end of the lever a max of 40 cm down, what is the closest you can position the pivot to the boulder and how much force would you need?

Answer 1

5. You are holding a rope that goes over a pulley and then wraps around pulleys per the diagram. Can you pull with enough force to lift the platform that you are standing on? How much do you weigh and how much do you need to pull?

Sol:

ооо T ооот T

Here mechanical advantage of pulley system is 7

Hence if wieght of plateform is less than 7 times of our body weight then we can lift the plateform.

If weight of plate form is negligible and my body weight is 800 N then i have to pull it with 10 N force to lift myself.

Because if i will pull the rope with 10 N force my effective weight will become 80-10 = 70 N and to lift 70N weight only 10 N pull is required.