Physics Lecture 4: Fundamental Forces

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Questions and Answers

What is the first fundamental force mentioned in the lecture?

Magnetic force
Electrical force
Gravitational force (correct)
Nuclear force

What is the second fundamental force mentioned in the lecture?

Magnetic force
Gravitational force
Electrical force (correct)
Strong nuclear force

How many fundamental forces are mentioned in the lecture?

3 (correct)
5
2
4

What is the third fundamental force mentioned in the lecture?

None of the above (it's not mentioned) (D) Signup and view all the answers

What is not a fundamental force mentioned in the lecture?

Magnetic force (C) Signup and view all the answers

In a third-class lever, where is the force located in relation to the fulcrum and load?

Between the load and the fulcrum (B) Signup and view all the answers

What is the function of the biceps muscle in the elbow joint example?

It performs the work (D) Signup and view all the answers

What type of lever is the elbow joint an example of?

Third-class lever (D) Signup and view all the answers

What is the name of the muscle mentioned in the elbow joint example?

Biceps muscle (C) Signup and view all the answers

What is the load in the elbow joint example?

The book (A) Signup and view all the answers

What is the approximate ratio of the electrical force to the gravitational force between an electron and a proton in a hydrogen atom?

1039 times greater (B) Signup and view all the answers

Which of the following is an example of electrical force?

The force between an electron and a proton in a hydrogen atom (D) Signup and view all the answers

What is true about the electrical force between an electron and a proton in a hydrogen atom?

It is stronger than the gravitational force (B) Signup and view all the answers

Which of the following particles is involved in the electrical force in a hydrogen atom?

Electron and proton (C) Signup and view all the answers

What is the direction of the electrical force between an electron and a proton in a hydrogen atom?

Attractive (A) Signup and view all the answers

What is the unit of acceleration due to gravity?

cm/sec2 (A), m/sec2 (B) Signup and view all the answers

What is the force that causes our weight?

Gravitational force (D) Signup and view all the answers

What is a medical effect of gravitational force?

Formation of varicose veins (B) Signup and view all the answers

What is the direction of the venous blood flow in the legs?

Against the force of gravity (D) Signup and view all the answers

What is the unit of force in the given formula: f = mg?

Newton (B) Signup and view all the answers

What is the direction of the force labelled N?

Perpendicular to the surface (D) Signup and view all the answers

What type of force is responsible for the horizontal reaction component FH?

Frictional force (A) Signup and view all the answers

What is the relationship between the force N and the surface?

The force N is supplied by the surface (C) Signup and view all the answers

What is the role of the surface in providing the force N?

It supplies the force N (D) Signup and view all the answers

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Study Notes

Fundamental Forces

There are three fundamental forces: gravitational force, electrical force, and a third force (not specified).

Gravitational Force

Gravitational force is the attraction between two objects with mass.
It is denoted by F = mg, where m is the mass and g is the acceleration due to gravity (cm/sec2 or m/sec2).
Example: Our weight is due to the attraction between the Earth and our bodies.
Medical effects of gravitational force include:
- Formation of varicose veins in the legs as venous blood travels against gravity to the heart.

Electrical Force

Electrical force is the force between electrically charged particles.
Example: The electrical force between an electron (ē) and proton (p+) in a hydrogen atom is about 1039 times greater than the gravitational force between them.

Forces in the Body

Levers in the Body

A third-class lever is a type of lever where the force is between the fulcrum and load.
Example: The elbow joint is a third-class lever in the human body.
- When lifting a book, the elbow joint is the fulcrum across which the biceps muscle performs the work.
- The vertical reaction force (N) is supplied by the surface, and the horizontal reaction component (FH) must be supplied by frictional force.