Year 8 Physical Science examples and explanations Flashcards
Explain and provide examples
Why is it important to understand about energy?
Energy is essential to everyday activities like cooking, using electronics, and transportation. Understanding its role can promote conscious consumption and better environmental stewardship.
Explain why the energy in food is usually stated in kilojoules rather than joules.
The energy in food is typically stated in kilojoules rather than joules because a joule is a very small unit of energy. Kilojoules provide a more practical and manageable way to represent the larger amounts of energy contained in food.
Describe situations in which kinetic energy could cause damage
Kinetic energy can cause damage when moving objects collide with something. For example, a fast-moving car can cause serious damage in a crash, or a baseball hit with a lot of force can break a window. The more speed and mass an object has, the more kinetic energy it has, which can result in greater damage during an impact.
What is the difference between kinetic and potential energy?
Kinetic energy varies with mass and speed, while potential energy depends on an object’s position.
Why is the distinction between kinetic and potential energy important. Give an example.
This distinction is essential in fields such as physics and engineering, informing the design of systems like roller coasters or vehicles.
Explain why sound energy could be considered a type of kinetic energy.
Sound energy can be considered a type of kinetic energy because it is created by the movement or vibration of particles in a medium, like air, water, or solids. These vibrations transfer energy through the medium, causing particles to move, which is the essence of kinetic energy—the energy of motion.
Give an example for each of the following:
Sound energy
Light energy
Electrical energy
Sound energy: music playing from a speaker, where vibrations create sound waves that travel through the air to your ears.
Light energy: sunlight, which provides energy that helps plants grow through photosynthesis.
Electrical energy: Static electricity, electromagnetic fields, lightning.
The following objects have potential energy.
Classify each one as an example of gravitational potential energy, chemical potential energy or elastic potential energy.
*A piece of chocolate cake
*A stretched spring
*A glass of cola
*An empty coffee mug on a table
*A teaspoon of sugar
*A cardboard box
*A 9 Volt battery
*A painter at the top of a ladder
*A banana
*A squashed tennis ball
*A piece of chocolate cake – Chemical potential energy
*A stretched spring – Elastic potential energy
*A glass of cola – Chemical potential energy
*An empty coffee mug on a table – Gravitational potential energy
*A teaspoon of sugar – Chemical potential energy
*A cardboard box – Gravitational potential energy (if it’s elevated or could fall)
*A 9 Volt battery – Chemical potential energy
*A painter at the top of a ladder – Gravitational potential energy
*A banana – Chemical potential energy
*A squashed tennis ball – Elastic potential energy
Explain what the law of conservation of energy means, using an example.
The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. For example, when you ride a bike down a hill, gravitational potential energy is transformed into kinetic energy as you speed up. The total amount of energy stays the same, but it changes form during the process.
Refer to the law of conservation of energy and state whether the following statement is true or false.
If energy is lost from one object, then it will be gained by
another.
True. Energy is transferred from one object to another or changes form, but the total amount remains constant.
Refer to the law of conservation of energy and state whether the following statement is true or false.
The total amount of energy in the universe is always changing.
False. According to the law of conservation of energy, the total amount of energy in the universe remains constant.
Refer to the law of conservation of energy and state whether the following statement is true or false.
If energy is wasted, then it is lost altogether.
False. Energy is never lost, but it may be transformed into less useful forms, such as heat.
Give an example of energy transformation
A hydroelectric power plant, kinetic energy from flowing water is transformed into electrical energy.
Give an example of wasted energy
In a car engine, some of the energy from fuel is converted into motion, but a significant amount is lost as heat, which is considered wasted energy.
Give an example of energy transfer
Heat transfer from a hot pan to food: When you place food in a hot pan, thermal energy (heat) transfers from the pan to the food, cooking it.
Electrical energy to light: When you turn on a light bulb, electrical energy transfers into the bulb and is transformed into light energy and thermal energy.
Describe the energy transformation(s) that take place when you cook rice in a microwave oven.
Electrical Energy to Microwave Radiation: The microwave oven uses electrical energy to generate microwave radiation.
Microwave Radiation to Thermal Energy: The microwave radiation is absorbed by the water molecules in the rice, causing them to vibrate and generate heat (thermal energy), which cooks the rice.
