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You and a friend are moving a 100kg sofa up some stairs. You each take one end a

ID: 1903703 • Letter: Y

Question

You and a friend are moving a 100kg sofa up some stairs. You each take one end and exert a vertical (upwards) force on the bottom corner where you are holding it. The sofa is angled as shown in the diagram. Which person has to exert the larger force on the sofa? What force does each person exert?

You and a friend are moving a 100kg sofa up some stairs. You each take one end and exert a vertical (upwards) force on the bottom corner where you are holding it. The sofa is angled as shown in the diagram. Which person has to exert the larger force on the sofa? What force does each person exert?

Explanation / Answer

Balancing moments about COM,

-FL*1.4+FR*0.7=0

FR=2FL

The person on the right has to exert a greater force.

Balancing forces,

FR+FL=100g

3FL=100g

FL=100g/3=327N

FR=653N