Levers AS91326

Summary

This video explores the role of levers in the human body, explaining how they function as simple machines to move loads with force. It covers the three classes of levers—first, second, and third class—and provides real-world examples like seesaws, wheelbarrows, and baseball bats. The human body lever examples include the neck, calf, and bicep muscles. Additionally, the video demonstrates how levers can be designed for speed or force, such as the golfer’s swing or a builder lifting heavy objects. The video encourages learning through tasks and further exploration in future lessons.

Takeaways

• 😀 Levers are simple machines that help move large loads with a set amount of force and can increase the speed of movement.
• 😀 The human body utilizes levers to perform different functions by applying force to move loads more effectively.
• 😀 A lever consists of a fulcrum (pivot point), effort (force applied), load (object being moved), effort arm (distance from fulcrum to effort), and resistance arm (distance from fulcrum to load).
• 😀 A first-class lever has the fulcrum between the effort and the load. In the human body, the neck joint acts as a fulcrum with muscles providing the effort and the skull as the load.
• 😀 A second-class lever has the load between the effort and the fulcrum. In the human body, a calf raise is an example of this type of lever, with toes as the fulcrum and the calf muscle as the effort.
• 😀 A third-class lever has the effort applied between the fulcrum and the load. A bicep curl is a third-class lever where the elbow is the fulcrum, the load is in the hand, and the bicep provides the effort.
• 😀 Most levers in the human body are third-class levers, such as the elbow joint during movement.
• 😀 The length of the effort arm and resistance arm of a lever can be adjusted to either increase speed or lift heavy objects.
• 😀 A lever designed for speed has a short effort arm and a long resistance arm, as seen in a golfer's swing.
• 😀 A lever designed for lifting heavy objects has a short resistance arm and a long effort arm, which allows more force to be applied, as seen in construction work.

Q & A

What is a lever?

A lever is a simple machine that helps transmit force, allowing large loads to be moved with a set amount of force, often more quickly than without it.

What are the main components of a lever?

The main components of a lever are the pivot point (fulcrum), the effort (where force is applied), the load (the object being moved), the effort arm (distance from the fulcrum to the effort), and the resistance arm (distance from the fulcrum to the load).

What is the difference between the effort arm and the resistance arm?

The effort arm is the distance from the fulcrum to where the effort (force) is applied, while the resistance arm is the distance from the fulcrum to the load (the object being moved).

What is a first-class lever?

A first-class lever has the fulcrum placed between the effort and the resistance. A real-world example is a seesaw. In the human body, the neck joint acts as a fulcrum, with the muscles providing the effort and the skull representing the load.

Can you give an example of a second-class lever?

An example of a second-class lever is a wheelbarrow, where the load is between the fulcrum and the effort. In the human body, a calf raise demonstrates this, with the toes acting as the fulcrum and the calf muscle providing the effort to lift the leg weight.

What distinguishes a third-class lever from the other two types?

In a third-class lever, the effort is placed between the fulcrum and the resistance. A real-world example is a baseball bat. In the human body, the bicep curl acts as a third-class lever, with the elbow as the fulcrum, the load in the hand (such as a dumbbell), and the biceps providing the effort.

Why are most levers in the human body third-class levers?

Most levers in the human body are third-class levers because they are designed for speed and movement. The positioning of the effort between the fulcrum and the load allows for faster movements, even though it may require more force to lift heavy objects.

How do levers in the human body help in lifting heavy objects?

Levers in the body can be manipulated to lift heavy objects by adjusting the lengths of the effort arm and the resistance arm. A lever designed for lifting heavy objects typically has a short resistance arm and a long effort arm, enabling greater force to be applied.

How can levers be designed for speed?

Levers designed for speed usually have a short effort arm and a long resistance arm, which allows them to generate higher speeds. An example of this design is seen in a golfer's swing, where the effort arm is short, but the resistance arm is long, generating high speed.

What role does the muscle tendon play in lever systems in the human body?

In the human body, the muscle tendon plays a crucial role by applying force at the insertion point of the bone across a joint. This allows the muscle to produce force and move the load using the lever system.