Tension

Definition

Tension is the force exerted by a string, rope, or cable when it is pulled tight by forces acting from opposite ends. It is a contact force that acts along the length of the medium and transmits force between objects.

5 Must Know Facts For Your Next Test

1. Tension always acts along the direction of the string or rope.
2. In a massless and frictionless pulley system, tension remains constant throughout the entire length of the rope.
3. Tension can be calculated using Newton's Second Law: sum of forces equals mass times acceleration ($\sum F = ma$).
4. When dealing with an object in equilibrium, tension must balance other forces such as gravity or friction.
5. The units of tension are Newtons (N), consistent with other forms of force.

Review Questions

• What happens to tension in a rope if it passes over a frictionless pulley?
• How does tension relate to Newton's Second Law?
• Why must tension balance other forces in an equilibrium scenario?

Related terms

Normal Force:

The perpendicular contact force exerted by a surface on another object.

Friction:

The resistive force that acts parallel to two surfaces in contact, opposing their relative motion.

Newton's Second Law:

$\sum F = ma$, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.