Tension Problems

What is Tension?

• Tension is defined as a force transmitted along a rope, chain, or wire.

• Tension will remain constant throughout the length of the rope.

• Tension is treated as a force in force diagrams and calculations

• Tension is measured in force units. (Newtons, dynes, or pounds (yuk!))

Weight or mass? What’s the difference?

• Mass is the amount of matter that an object is made up of, measured in g, kg, slugs

• The mass of an object remains constant at any location in the universe unless matter is added or removed

• Weight is the force of gravity acting on an object, measured in force units (N, dynes, or pounds)

• Weight depends on the acceleration due to gravity for the location of the object.

• Weight (w) = mg

Problems in Equilibrium

• Since the object has no acceleration, the net force is equal to zero

• The y-components of tension should be equal to the objects weight (Fy=0)

• The forces in the x-direction should cancel each other (Fx=0)

Force Diagram(Free-Body Diagram)

W=mg

Ta Tb

1 2

Tbx=Tbcos2

Tby=Tbsin2Tay=Tasin1

Tax=Tacos1

Applying Newton’s 2nd Law

θ1 θ2

Ta Tb

Since the sign is in equilibrium, the net force must be equal to zero.

Fy = Ta sin θ1+Tb sin θ2-W = 0

Fy =Ta cos θ1 -Tb cos θ2 = 0

W=mg