8.6.1. Muscular Force

Can you push or lift a book lying on a table without touching it? Can you lift a bucket of water without holding it? Generally, to apply a force on an object, your body has to be in contact with the object. The contact may also be with the help of a stick or a piece of rope. When we push an object like a school bag or lift a bucket of water, where does the force come from? This force is caused by the action of muscles in our body. The force resulting due to the action of muscles is known as the muscular force.

Muscular force is the force generated by the action of muscles in our body when we exert effort to push, pull, or lift objects. For example, when you lift a bucket, you engage various muscles in your arms and back. These muscles contract, creating a force that helps you lift and move the object. Similarly, trying to move a heavy piece of furniture requires significant muscular effort, engaging multiple muscle groups in your body.

Think about how you lift a backpack full of books. You bend at the knees and use various muscles in your legs, back, and arms to raise the backpack. Without the action of these muscles, you wouldn't be able to lift it off the floor. This is similar to how animals like horses use their muscular force to pull heavy loads.

It is the muscular force that enables us to perform all activities involving movement or bending of our body. In Class VII you have learnt that in the process of digestion the food gets pushed through the alimentary canal. Could it be a muscular force that does it? You also know that lungs expand and contract while we inhale and exhale air during breathing. Where are these muscles located which make breathing possible? Can you list a few more examples of the force exerted by the muscles in our body? Animals also make use of muscular force to carry out their physical activities and other tasks. Animals like bullocks, horses, donkeys, and camels are used to perform various tasks for us.

Muscular force is vital not just for lifting and moving objects but also for numerous bodily functions. In digestion, muscular force is involved as muscles in the digestive tract push food along its path. Similarly, muscles in the chest wall help expand and contract the lungs during breathing, allowing us to inhale fresh air and exhale carbon dioxide. Various animals in agriculture or transport, such as horses and donkeys, also use muscular force to perform laborious tasks. These examples highlight the importance and versatility of muscular force in both human activities and nature.

Imagine your stomach muscles working to digest a large meal after a feast. These muscles push food through your digestive system much like a conveyor belt moves products in a factory. In the same way, when farmers use oxen to plow fields, they rely on the strong muscular force of the animals to accomplish the heavy work.

Since muscular force can be applied only when it is in contact with an object, it is also called a contact force. Are there other types of contact forces? Let us find out.

Muscular force is classified as a contact force because it requires direct physical interaction between the body (or muscle) and the object being acted upon. This means you have to touch or hold the object to apply the force. For instance, when you push a desk, your hand is contacting the desk, allowing the muscular force to transfer to it. Understanding contact forces helps clarify how we interact with various objects, and it leads us into exploring other types of forces that also require contact.

Consider playing basketball, where to shoot the ball, you must apply a force directly with your hands. As you bounce the ball, the muscular force you exert is only effective because your hands are in contact with the ball. This is similar to how friction acts as a contact force, helping the ball bounce properly on the court.

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