Short Answer

Tension in a string is the pulling force that acts along the length of a stretched string, rope, or cable. When both ends of a string are pulled, the string becomes tight, and a force develops inside it. This force is called tension.

Tension always acts along the string and pulls equally on both ends. It is the force that allows us to lift objects with a rope, tow vehicles, or hold something by tying a string. The string itself cannot push; it can only pull, which is why tension is always a pulling force.

Detailed Explanation :

Tension in string

Tension in a string is a fundamental concept in physics and plays an important role in understanding forces in everyday situations. Tension refers to the pulling force that is transmitted through a string, rope, cable, or chain when it is stretched by forces acting at both ends. To put it simply, when we pull a string, the string becomes tight, and a force builds up inside it. This internal pulling force is called tension.

Tension always acts along the length of the string and pulls outward from both ends. A string cannot push an object; it can only pull it. That is why tension is considered a pulling force. For example, when you pull a bucket of water from a well using a rope, the rope is under tension because it is stretched by your hand on one end and the bucket on the other. The rope transmits your pulling force to lift the bucket.

The amount of tension in a string depends on the forces applied at its ends. If the forces increase, the tension increases. If the forces decrease, the tension decreases. In an ideal string, which is assumed to be light and cannot stretch, the tension remains the same throughout its length. This simplifies problems in physics, especially in mechanics.

In real life, however, strings may stretch slightly depending on their material, but in basic physics we assume the string to be perfectly inextensible and massless. This assumption helps in solving numerical problems easily, because it means the tension value does not change at different points along the string.

Tension also depends on the orientation of the string. If the string is pulling an object horizontally, the tension acts horizontally. If the string is pulling an object upward, the tension acts upward. In every case, the direction of tension follows the direction of the string itself. This is why tension is called a directional force.

Consider the example of a hanging mass tied to a rope. The weight of the mass pulls the rope downward. This makes the rope stretch and creates an upward tension force. At equilibrium, the tension in the rope equals the weight of the mass. If the mass is heavier, the tension is greater.

Tension also appears when two people pull a rope in opposite directions, such as in the game of tug-of-war. Even though both sides are pulling, the rope remains tight because equal and opposite forces are applied at both ends. The tension inside the rope is equal to the force applied by each person.

Another important example is when a block is being pulled along a surface using a string. If the pulling force is 20 N, the tension in the string is also 20 N, provided the string is ideal. The tension transmits the applied force from the hand to the block and causes it to move forward.

Tension can also act at angles. When two strings are used to hold a single object, such as a ceiling lamp tied with two wires, each wire carries tension, and their combined effect balances the weight of the lamp. Here, the tension depends on the angle at which the wires are attached. The more horizontal the wires are, the greater the tension needed to hold the object.

In rotating systems, tension plays a role in providing centripetal force. For example, when you tie a stone to a string and rotate it in a circle, the string becomes tight because the stone pulls outward. The tension in the string provides the inward force needed to keep the stone moving in a circular path.

Tension is also important in engineering structures like bridges, cranes, and elevators. Elevator cables carry the tension force to hold and lift the cabin. Suspension bridges use strong steel cables that handle enormous tension forces to support the weight of the bridge deck and the vehicles moving over it.

In summary, tension in a string arises whenever a string or rope is pulled from both ends. It acts along the string, is always a pulling force, and depends on the forces applied at the ends. Understanding tension helps us analyze various mechanical systems and solve many physics problems involving ropes, pulleys, and hanging objects.

Conclusion

Tension in a string is the internal pulling force that appears when a string, rope, or cable is stretched by forces at both ends. It always acts along the string and transmits force from one end to the other. This concept is essential in studying motion, forces, and simple machines.