What is torque?

Torque is a concept used in physics and engineering to describe the rotational force applied to an object around a specific axis. It is a vector quantity that represents the tendency of a force to cause rotational motion. Torque is often associated with rotating objects and is measured in units such as Newton-meters (Nm) or foot-pounds (ft-lb).

Fig 1. Torque Animation 

(link from https://upload.wikimedia.org/wikipedia/commons/0/09/Torque_animation.gif)

Key points about torque:

1. Definition: Torque can be defined as the product of a force and the perpendicular distance from the axis of rotation to the line of action of the force. Mathematically, torque (τ) is given by the equation:

τ = r * F * sin(θ)

where τ is the torque, r is the distance from the axis of rotation to the point where the force is applied, F is the force, and θ is the angle between the force and the line connecting the axis of rotation and the point of application.

2. Rotational Effect: Torque describes the rotational effect or turning force exerted on an object. It causes objects to rotate or change their rotational motion.
3. Moment Arm: The distance between the axis of rotation and the point where the force is applied is known as the moment arm or lever arm. Increasing the moment arm increases the torque produced by a given force.
4. Direction: Torque is a vector quantity and has both magnitude and direction. The direction of torque is determined by the right-hand rule. When viewed from the direction of the applied force, the thumb points in the direction of the torque.
5. Units: Torque is typically measured in Newton-meters (Nm) or foot-pounds (ft-lb). One Newton-meter is the torque produced by a one Newton force applied at a distance of one meter from the axis of rotation.
6. Application: Torque is essential in various applications, such as rotating machinery, engines, motors, and mechanical systems. It is used to measure and control rotational forces, determine the effectiveness of tools, and analyze the stability of objects in rotational motion.

Understanding torque is crucial in engineering fields, including mechanics, robotics, and automotive industries. It helps in designing and analyzing systems that involve rotational motion and provides insights into the behavior of rotating objects and their response to applied forces.

Learn more:

http://hyperphysics.phy-astr.gsu.edu/hbase/tord.html

https://www.thoughtco.com/calculating-torque-2698804

https://www.geeksforgeeks.org/torque/

What is speed?

Speed refers to the rate at which an object moves or covers a certain distance in a given amount of time. It is a scalar quantity that represents the magnitude of the object's velocity. Speed is typically measured in units such as meters per second (m/s), kilometers per hour (km/h), or miles per hour (mph).

Figure 1. Speed

Key points about speed:

1. Scalar Quantity: Speed is a scalar quantity, which means it only has magnitude and does not have a specific direction associated with it. It tells us how fast an object is moving but not the direction of its motion.
2. Calculation: Speed is calculated by dividing the distance traveled by the time taken to cover that distance. The formula for speed is:

Speed = Distance / Time

For example, if a car travels 100 kilometers in 2 hours, its speed would be 50 km/h (100 km divided by 2 hours).

3. Instantaneous Speed vs. Average Speed: Instantaneous speed refers to the speed of an object at a specific moment in time, while average speed is the total distance traveled divided by the total time taken. Average speed gives an overall measure of how fast an object is moving over a certain period.
4. Speed and Velocity: While speed and velocity are often used interchangeably in everyday language, they have distinct meanings in physics. Velocity is a vector quantity that includes both speed and direction. It specifies both how fast an object is moving and in which direction.
5. Speed and Acceleration: Speed is related to acceleration, which is the rate of change of velocity. When an object accelerates, its speed changes. Positive acceleration results in an increase in speed, while negative acceleration (deceleration) leads to a decrease in speed.
6. Speed and Motion: Speed is a fundamental concept in the study of motion and is used to describe the movement of objects in various contexts, such as in sports, transportation, and physics.

You can see the video on external resources:

•  https://study.com/academy/lesson/measuring-the-speed-of-an-object-physics-lab.html 

It's important to note that speed alone does not provide a complete description of an object's motion. To fully understand the motion, the direction and magnitude of velocity need to be considered.

 

What is Voltage?

Voltage, also known as electric potential difference, is a fundamental concept in electricity and electrical circuits. It refers to the potential energy difference per unit charge between two points in an electric field. Voltage is measured in units called Volts (V) and is denoted by the symbol "V."

In simple terms, voltage can be thought of as the "push" or "force" that drives electric charges to move within a circuit. It represents the potential energy that an electric charge possesses due to its position in an electric field.

Fig 1. Voltage. 

Fig 2 Analogy (cite from: https://www.electricaltechnology.org/)

Key points about voltage:

1. Potential Difference: Voltage represents the difference in electric potential between two points in a circuit. It is measured by comparing the electric potential at one point to the electric potential at another point.
2. Electromotive Force (EMF): Voltage is often referred to as electromotive force (EMF). EMF is the energy per unit charge provided by a source, such as a battery or generator, to establish an electric potential difference in a circuit.
3. Unit of Measurement: Voltage is measured in Volts (V). One Volt is defined as the potential difference across a conductor when a current of one Ampere flows through it, and the power dissipated is one Watt.
4. Polarity: Voltage has polarity, which indicates the direction of the potential difference between two points. It signifies the positive and negative ends of a voltage source or the terminals of a circuit element.
5. Voltage Sources: Voltage can be provided by various sources, including batteries, generators, power supplies, and electrical outlets. These sources create a potential difference that enables the flow of electric current in a circuit.
6. Voltage and Current: Voltage is closely related to current in Ohm's Law. Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance. Mathematically, Ohm's Law can be expressed as:

I = V / R

where I is the current, V is the voltage, and R is the resistance.

Voltage is a fundamental concept in understanding the behavior of electrical circuits, including the flow of electric current, power dissipation, and the operation of electronic devices. It plays a crucial role in various applications, ranging from powering electronic devices to electrical distribution systems.

External animation:

https://www.furryelephant.com/lib/img/elec-redirect.gif

What is electron?

An electron is a subatomic particle that carries a negative electric charge. It is one of the fundamental particles that make up an atom. Electrons are found outside the atomic nucleus in regions called electron shells or energy levels.

Figure 1. Electron 

(Cited from https://www.sciencefacts.net/wp-content/uploads/2020/11/Electron-Diagram.jpg)

Key characteristics of electrons include:

1. Charge: Electrons have a negative electric charge (-1 elementary charge). This charge is equal in magnitude but opposite in sign to the positive charge carried by protons.
2. Mass: Electrons have a much smaller mass compared to protons and neutrons. The mass of an electron is approximately 1/1836th of the mass of a proton.
3. Behavior: Electrons exhibit properties of both particles and waves, known as wave-particle duality. They can behave as discrete particles and also display wave-like characteristics, such as interference and diffraction.
4. Energy Levels: Electrons occupy specific energy levels around an atomic nucleus. These energy levels, also known as electron shells or orbitals, are quantized, meaning they can only have certain discrete values.
5. Electron Cloud: Electrons do not follow a fixed path or orbit around the nucleus. Instead, they are described by a probability distribution known as the electron cloud or electron orbital. The electron cloud represents the region where an electron is most likely to be found.
6. Charge and Matter Interactions: Electrons play a crucial role in chemical reactions and the formation of chemical bonds. Their interactions with other atoms determine the electrical and chemical properties of substances.

Electrons are fundamental to the understanding of electricity, magnetism, and the behavior of matter at the atomic and subatomic level. They are also essential for the functioning of electronic devices and play a vital role in various fields of science, including physics, chemistry, and materials science.

External resources for learning:

https://www.sciencefacts.net/electron.html
https://www.techtarget.com/whatis/definition/electron

https://byjus.com/chemistry/electrons/

What is Current?

Current, in the context of electrical circuits, refers to the flow of electric charge through a conductor. It is the rate at which electric charges, typically electrons, move past a given point in a circuit. Current is measured in units called Amperes (A) and is denoted by the symbol "I."

Fig. 1 free electrons 

cited from: https://circuitglobe.com/electric-current.html 

Fig. 2 Flow of electron

cited from: https://circuitglobe.com/electric-current.html 

In simple terms, current is the flow of electrons or charge in a closed loop circuit. It is similar to the flow of water in a pipe. Just as water flows from a higher pressure to a lower pressure, electric current flows from a region of higher electric potential (voltage) to a region of lower electric potential.

There are two types of current:

1. Direct Current (DC): In a DC circuit, the flow of electric charge is unidirectional. The magnitude and direction of the current remain constant over time. Batteries and most electronic devices operate on DC.
2. Alternating Current (AC): In an AC circuit, the flow of electric charge periodically changes direction. The magnitude and direction of the current vary sinusoidally with time. AC is commonly used for power distribution in homes and businesses.

Fig. 3 Analogy 

(link from https://eschooltoday.com/learn/wp-content/uploads/2020/10/explain-current-and-voltage.jpg)

The behavior of current in a circuit is governed by Ohm's Law, which states that the current (I) flowing through a conductor is directly proportional to the voltage (V) across the conductor and inversely proportional to its resistance (R). Mathematically, Ohm's Law can be expressed as:

I = V / R

where: I = Current (in Amperes) V = Voltage (in Volts) R = Resistance (in Ohms)

Current is a fundamental quantity in electrical circuits and plays a crucial role in determining the behavior and operation of various electronic components and devices.

Good external resources:

https://eschooltoday.com/learn/current-electricity/
https://circuitglobe.com/electric-current.html