Technical Science - Term 1 - Week 2

Energy is the ability to do work, and it exists in various forms. The two primary forms of energy are kinetic energy, which is the energy of motion, and potential energy, which is stored energy based on an object's position or state. For example, a moving car has kinetic energy, while a drawn bow has potential energy. The total energy in a closed system remains constant, as stated by the law of conservation of energy.

To calculate kinetic energy (KE), we use the formula KE = 1/2 mv², where m is mass in kilograms and v is velocity in meters per second. For example, if a car with a mass of 1000 kg is traveling at 20 m/s, its kinetic energy would be KE = 1/2 * 1000 * (20)² = 200,000 J. For potential energy (PE), the formula is PE = mgh, where h is height in meters and g is the acceleration due to gravity (approximately 9.81 m/s²). If the same car is at a height of 10 m, its potential energy would be PE = 1000 * 9.81 * 10 = 98,100 J.

Consider a roller coaster at the top of a hill. Discuss with your partner how the energy changes as the coaster descends. Initially, the coaster has maximum potential energy at the top due to its height. As it descends, this potential energy is converted into kinetic energy, increasing the speed of the coaster. By the time it reaches the bottom, most of its potential energy has transformed into kinetic energy, illustrating the conservation of energy principle.

Complete the following exercises: 1) Calculate the kinetic energy of a bicycle with a mass of 15 kg traveling at 5 m/s. 2) A rock weighing 2 kg is held at a height of 3 m. Calculate its potential energy. 3) Describe an everyday example of energy transformation and explain the forms of energy involved.

• Energy stored in an object
• Energy of motion
• Energy due to height
• Energy that cannot be transformed

Answer: Energy of motion

Kinetic energy is defined as the energy an object possesses due to its motion.

• A car driving on a highway
• A compressed spring
• A flowing river
• A person running

Answer: A compressed spring

A compressed spring stores energy due to its position, making it an example of potential energy.

Answer: Energy cannot be created or destroyed, only transformed from one form to another.

This law states that the total energy in a closed system remains constant.

• It increases
• It decreases
• It remains the same
• It transforms into thermal energy

Answer: It decreases

As an object falls, its height decreases, leading to a decrease in potential energy.

Answer: As the pendulum swings, potential energy at the highest point transforms into kinetic energy at the lowest point.

The energy transformation occurs as the pendulum moves between its highest and lowest points.

• PE = mv²
• PE = mgh
• PE = 1/2 mv²
• PE = mgh²

Answer: PE = mgh

Potential energy is calculated using the formula PE = mgh, where m is mass, g is gravity, and h is height.

• Potential energy
• Kinetic energy
• Chemical energy
• Nuclear energy