Forces in the Human Body

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Questions and Answers

What is the force that resists the motion between two surfaces in contact?

Frictional force (correct)

Normal force

Kinetic force

Static force

What is the coefficient of static friction (µs) used to find?

The force needed to keep an object moving

The force of kinetic friction

The minimum resistance force an object can exert before it starts to move

The maximum resistance force an object can exert before it starts to move (correct)

What is the relationship between the coefficient of static friction (µs) and the coefficient of kinetic friction (µk)?

µs < µk

µs = µk

µs is independent of µk

µs > µk (correct)

What is the force transmitted from the foot to the ground when a person walks?

Frictional force Signup and view all the answers

What is the formula for the maximum force of friction (Ff)?

Ff = µN Signup and view all the answers

What is the value of the coefficient of friction (µ) dependent on?

The materials of the two surfaces in contact Signup and view all the answers

What is the unit of acceleration due to gravity?

m/sec2 Signup and view all the answers

Which force is responsible for the formation of varicose veins in the legs?

Gravitational force Signup and view all the answers

What is the formula for gravitational force according to Newton's law?

F = mg Signup and view all the answers

What is the medical consequence of gravity on the skeleton?

It contributes to healthy bones Signup and view all the answers

What is the electrical force responsible for in the body?

The control of muscles Signup and view all the answers

What is the stronger force between an electron and a proton in a hydrogen atom?

Electrical force Signup and view all the answers

What is the primary function of the nuclear force?

To bind protons and neutrons Signup and view all the answers

What is the relationship between the electrical force and muscle movement?

The electrical force causes muscle movement Signup and view all the answers

How much stronger is the nuclear force compared to the chemical binding that holds atoms together in molecules?

10 million times Signup and view all the answers

What is the classification of levers based on in the body?

The position of the fulcrum, effort, and load Signup and view all the answers

Which type of lever is most common in the body?

Third-class lever Signup and view all the answers

What is the term that refers to an opposing force, such as weight?

Load Signup and view all the answers

What is the role of the fulcrum in a lever system?

To pivot the action Signup and view all the answers

What is the example of a first-class lever in the human body?

The joint between the skull and the atlas vertebrae Signup and view all the answers

What is the characteristic of a second-class lever?

The load is between the fulcrum and the force Signup and view all the answers

What is the example of a third-class lever in the human body?

The elbow joint Signup and view all the answers

Study Notes

Forces on and in the Body

There are three fundamental forces: gravitational force, electrical force, and strong nuclear force
Gravitational force:
- Attracts any two objects, according to Newton's law (F = mg)
- Medical consequences include varicose veins in the legs and bone health
Electrical force:
- More complicated than gravity, involving attractive and repulsive forces between static electrical charges
- Example: electrical force between an electron and proton in a hydrogen atom is 1039 times greater than gravitational force
- Our bodies are electrical machines, with muscles controlled by electrical charges
Nuclear force:
- Binds protons and neutrons into atomic nuclei
- About 10 million times stronger than chemical binding in molecules

Levers in the Body

Many muscle and bone systems act as levers
Levers are classified into three classes based on the positions of the fulcrum, effort, and load
Third-class levers are most common in the body
Bones can act as levers, with the effort being the force applied by muscles and the load being the weight resisted

Types of Levers

First-class lever: effort and load are on opposite sides of the fulcrum
- Example: joint between skull and atlas vertebrae of the spine
Second-class lever: load is between the fulcrum and force
- Example: Achilles tendon
Third-class lever: force is between the fulcrum and load
- Example: elbow joint when lifting a book

Frictional Force

A force that resists motion between two surfaces in contact
Depends on the nature of the surface and is independent of the surface area
Two types of frictional force:
- Static friction (Fs): the maximum force an object can exert before it starts to move
- Kinetic friction (Fk): the force required to keep an object moving
Friction in the body:
- Disorders like arthritis can cause increased friction in bone joints
- Friction is significant when walking, with vertical and horizontal components of force transmitted from the foot to the ground

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Description

A quiz on the fundamental forces acting on and in the human body, including gravitational, electrical, and nuclear forces.