Physics Lecture 5: Force on and in the Body
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Questions and Answers

What is a force?

Force is an external agent capable of changing a body's state of rest or motion.

What are two categories of forces we can experience?

Forces we are unaware of inside the body, and forces we are aware of on the body.

What are the two types of forces that affect the body?

  • Both A and B (correct)
  • Forces in the body
  • Forces on the body

What are the categories of forces that affect the body?

<p>Both A and B (C)</p> Signup and view all the answers

What is the equation for the force of gravity on earth?

<p>F = m * g</p> Signup and view all the answers

What is one of the important medical effects of gravity?

<p>The formation of varicose veins in the legs.</p> Signup and view all the answers

Gravity has a positive effect on the skeleton.

<p>True (A)</p> Signup and view all the answers

Briefly define electrical force.

<p>Electrical force is a type of interaction that occurs between two charged bodies.</p> Signup and view all the answers

What is one impact of electrical forces in the body?

<p>Control and action of our muscles is primarily electrical.</p> Signup and view all the answers

Electrical eels are able to produce a stunning voltage.

<p>True (A)</p> Signup and view all the answers

What are the two types of nuclear forces?

<p>The strong nuclear force and the weak nuclear force.</p> Signup and view all the answers

What is the main function of frictional force?

<p>Frictional force limits the efficiency of machines such as electrical generators and automobiles.</p> Signup and view all the answers

Where do we use frictional forces?

<p>When our hands grip a rope, when we walk or run, and in devices such as automobile brakes.</p> Signup and view all the answers

Friction in bone joints is usually much lower than in engineering-type materials.

<p>True (A)</p> Signup and view all the answers

What aspect of frictional force is still controversial?

<p>The exact behavior of synovial fluid in the joint.</p> Signup and view all the answers

What diseases are known to increase friction in bone joints?

<p>Arthritis.</p> Signup and view all the answers

What is the vertical reaction force supplied by the surface called?

<p>The vertical reaction force is labeled N.</p> Signup and view all the answers

What equation is used to calculate the horizontal component of friction?

<p>F = µN</p> Signup and view all the answers

What is static equilibrium?

<p>Static equilibrium is a state where the body is at rest and in equilibrium.</p> Signup and view all the answers

What conditions must be met for static equilibrium?

<p>The sum of the forces acting on the body must be zero in any direction, and the sum of the torques about any axis must also equal zero.</p> Signup and view all the answers

What are levers?

<p>Levers are simple machines that allow the application of force to perform tasks such as lifting or moving objects.</p> Signup and view all the answers

What are the three types of levers?

<p>First-class, second-class, and third-class.</p> Signup and view all the answers

Where is the fulcrum located in a first-class lever?

<p>Between the applied force and the resistance.</p> Signup and view all the answers

What is a common medical example of a first-class lever?

<p>The use of forceps during childbirth.</p> Signup and view all the answers

Where is the resistance located in a second-class lever?

<p>The resistance is located between the fulcrum and the applied force.</p> Signup and view all the answers

What common object is an example of a second-class lever?

<p>A wheelchair.</p> Signup and view all the answers

Where is the applied force located in a third-class lever?

<p>Between the fulcrum and the resistance.</p> Signup and view all the answers

What common medical example is used to illustrate a third-class lever?

<p>The use of forceps during dental procedures.</p> Signup and view all the answers

What tool or device is often used in medicine and is a good example of a lever?

<p>Levers, with their various types, are essential tools in medicine, allowing healthcare professionals to perform tasks with precision and efficiency.</p> Signup and view all the answers

What are the two most important muscles involved in the movement of the elbow?

<p>The biceps and the triceps.</p> Signup and view all the answers

What does the contraction of the triceps cause?

<p>The contraction of the triceps causes an extension, or opening, of the elbow.</p> Signup and view all the answers

How does the force exerted by a muscle compare to the weight it holds up?

<p>The force exerted by the muscle is much greater than the weight it holds up.</p> Signup and view all the answers

What does the dynamic force play a key role in?

<p>The dynamic force is important when the body is moving and hitting another body.</p> Signup and view all the answers

How does the dynamic force relate to Newton's laws of motion?

<p>The dynamic force is based on Newton's second law, which states that force equals mass times acceleration.</p> Signup and view all the answers

What is the explanation for the dynamic force equation?

<p>Δ(mv) equals the change of momentum and Δt the interval of time.</p> Signup and view all the answers

The human body is a dynamic system that responds to internal and external stimuli.

<p>True (A)</p> Signup and view all the answers

Flashcards

Gravitational Force

The force that attracts objects towards the center of the Earth, moon, or other massive objects. This is also known as the object's weight.

Strong Nuclear Force

A fundamental force that binds protons and neutrons together in the nucleus of an atom.

Weak Nuclear Force

A very weak force that acts on quarks, the particles that make up protons and neutrons. It is responsible for beta decay.

Frictional Force

The force that opposes motion between two surfaces in contact. It is caused by the interactions between the molecules of the two surfaces.

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Static Force

A force that prevents an object from moving when a force is applied to it. It occurs when two surfaces are in contact and are not moving relative to each other.

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Dynamic Force

A force that causes an object to move. It is defined by Newton's second law: Force = Mass x Acceleration.

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First-Class Lever

A type of lever where the fulcrum is located between the applied force and the resistance. It can either amplify the force or provide precise control.

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Second-Class Lever

A type of lever where the resistance is located between the fulcrum and the applied force. It provides a mechanical advantage, allowing a smaller force to move a larger resistance.

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Third-Class Lever

A type of lever where the applied force is located between the fulcrum and the resistance. It does not provide a mechanical advantage but increases the range of motion and speed.

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Posture

The process by which the body maintains a stable posture against gravity. It involves continual adjustments to the center of gravity over the base of support.

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Mobility

The ability of the body to move smoothly and easily. It involves the coordinated action of muscles, bones, and joints.

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Applied Force

The force that is applied to an object. It can be a push or a pull.

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Resistance Force

The force that opposes the applied force. It is the weight of the object or the force required to overcome resistance.

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Fulcrum

The point around which a lever rotates. It is the pivot point of the lever system.

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Mechanical Advantage

The ability of a lever to multiply force. It is the ratio of the output force to the input force.

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Effort Arm

The distance from the fulcrum to the point where the force is applied.

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Resistance Arm

The distance from the fulcrum to the point where the resistance force is applied.

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Vein

A type of blood vessel that carries blood back to the heart.

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Varicose Veins

A condition characterized by enlarged and twisted veins, often in the legs.

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Bone Loss

The loss of bone mineral density due to lack of physical stress.

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Diffusion

The process by which atoms or molecules in a fluid move from an area of high concentration to low concentration.

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Passive Transport

The process by which a substance is transported across a membrane from an area of high concentration to low concentration.

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Active Transport

The process by which a substance is transported across a membrane from an area of low concentration to high concentration, requiring energy.

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Synovial Joint

A type of joint in the body that allows for movement in multiple directions.

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Synovial Fluid

A fluid found in synovial joints that helps to lubricate and nourish the joint.

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Arthritis

A condition that causes inflammation and pain in the joints.

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Homeostasis

The process by which the body maintains a stable internal environment.

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Muscular Response

A type of response that involves the contraction of muscles.

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Hormonal Response

A type of response that involves the release of chemicals from glands.

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Metabolism

The process by which the body produces energy from food.

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Digestion

The process by which the body breaks down food into smaller molecules.

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Excretion

The process by which the body eliminates waste products.

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Study Notes

Lecture 5: Force on and in the Body

  • Force is an external agent that changes a body's state of rest or motion. It has magnitude and direction.
  • The direction of the force is the direction in which it is applied.
  • The application point of the force is the point where the force is applied.

How Forces Affect the Body

  • Forces inside the body (unaware of): These include muscular forces that circulate blood and cause the lungs to take in air. They also include forces that determine where atoms and molecules stay in the body.
  • Forces on the body (aware of): These include the forces involved when we bump into objects.

The Force

  • Forces in the body:
    • Gravitational force
    • Nuclear force
    • Electrical force
  • Forces on the body:
    • Frictional force
    • Static force
    • Dynamic force

1- Gravitational Force

  • Gravity is the force with which Earth, the moon, or other large objects pull on other objects.
  • This is how objects are weighed.
  • On Earth, the force of gravity (weight) is calculated with the equation F = m * g.
    • Where:
      • F = force (weight)
      • m = mass
      • g = acceleration due to gravity (9.8 N/kg or 980 dyn/gm)
  • Gravity affects varicose veins and bone health (space travel, long-term bed rest).

2- Electrical Force

  • Electrical force is the interaction between charged bodies.
  • It can be attractive or repulsive.
  • It is described by Newton's laws of motion.
  • It is involved in muscle function and cell function in the body.

3- Nuclear Force

  • Strong nuclear force: A very strong, short-range (10-15 m) force holding atomic nuclei together.
    • It is the strongest fundamental force.
  • Weak nuclear force: An extremely short-range (10-18 m) force acting on quarks affecting proton/neutron structure and beta decay processes.

1- Frictional Force

  • Friction is everywhere, limiting the efficiency of many machines including electrical generators, automobiles etc
  • It acts to oppose motion between surfaces.
  • Friction must sometimes be overcome (in joints, but is small in healthy joints).
  • The friction coefficient of bone joints differs from engineered materials. Diseases affecting the joints, such as arthritis, can contribute to friction increase.
  • Friction is essential for our daily life (walking, gripping).

2- Static Force

  • Static forces allow the body to be at rest.
  • The sum of the forces and torques on the body must equal zero for static equilibrium.
  • Levers are simple machines that help in applying forces and moving objects.
  • The skeletal and muscular systems of the body use levers.

3- Types of Levers

  • First-class lever: Fulcrum is between the force and the resistance. (eg, using forceps during childbirth)
  • Second-class lever: Resistance is between the force and the fulcrum. (eg., wheelchair)
  • Third-class lever: Force is between the fulcrum and the resistance. (eg., dental procedures).

3- Dynamic Force

  • The human body is constantly responding to internal and external stimuli and is dynamic.
  • The center of gravity and the act of standing requires dynamic, continual movement.
  • Dynamic forces are important during movement, acceleration, and deceleration (eg., when moving and colliding with another object)
  • The equation for force is: F = Δ(mv)/Δt (force equals change in momentum divided by change in time).

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Forces in and on the Body PDF

Description

This quiz focuses on Lecture 5, which discusses the concept of force as it relates to the human body. It covers both internal and external forces that impact bodily function and movement. Test your understanding of gravitational, nuclear, and electrical forces, along with frictional, static, and dynamic forces.

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