Grade 10 Energy Test

Food contains chemical energy. This is because food is made up of molecules that can be broken down through chemical reactions to release energy. When we eat food, our bodies break down the molecules in the food through digestion, and this releases the stored chemical energy, which our bodies then use for various functions such as movement, growth, and maintaining body temperature.

The SI unit of energy is the joule. The joule is defined as the amount of energy transferred when a force of one newton is applied over a distance of one meter. It is commonly used to measure various forms of energy such as mechanical, thermal, and electrical energy. The watt is the SI unit of power, not energy. The newton is the SI unit of force, and the kilogram is the SI unit of mass.

The law of conservation of energy states that energy cannot be created or destroyed, but only transformed from one form to another. This means that the total amount of energy in a closed system remains constant. The option "Energy can be created in another form" contradicts this law, as it suggests that energy can be created, which goes against the principle of conservation.

Energy is the ability or capacity to do work. It is the power or agility to perform tasks and accomplish goals. Energy is required to push and pull objects, complete tasks, and carry out any form of work. It is the underlying force that enables actions and movements to occur.

Gravitational potential energy refers to the energy that an object possesses due to its position above a leveled surface. It is the energy that an object has when it is raised above the ground level. This energy is a result of the gravitational force acting on the object, and it can be converted into other forms of energy when the object falls or moves downward.

Mechanical energy is not a stage in the energy transformation of a flashlight. A flashlight works by converting chemical energy from the batteries into electrical energy, which then gets transformed into light energy. Mechanical energy, which refers to the energy associated with the motion or position of an object, is not involved in this process.

The potential energy of an object is given by the formula PE = mgh, where m is the mass, g is the acceleration due to gravity, and h is the height above ground. Rearranging the formula, we can solve for h: h = PE / (mg). Plugging in the values given, we get h = 32.4 J / (34000 g * 9.8 m/s^2). Converting grams to kilograms, we have h = 32.4 J / (34 kg * 9.8 m/s^2) = 0.097 m. Therefore, the height above ground is 0.097 m.

Weight is not needed to calculate potential energy because potential energy is determined by the height of an object and its mass, not its weight. Weight is a force that is dependent on the mass of an object and the acceleration due to gravity, but it is not directly used in the calculation of potential energy. Therefore, weight is not necessary to calculate potential energy.

Renewable energy sources are those that can be replenished naturally over a relatively short period. Solar energy, derived from the sun's radiation, is a renewable source as it is constantly being replenished. The other options are non-renewable sources, as they are finite and take millions of years to form.

Fuel is not a type of energy, but rather a substance that can be burned or consumed to produce energy. Energy can be derived from various sources such as thermal, nuclear, or strain, but fuel itself is not considered a type of energy. It is a material that can be converted into energy through various processes.

Thermal and electrical energy can both be described as "energy of movement" because they involve the movement of particles or charges. Thermal energy is the energy associated with the movement of atoms and molecules, while electrical energy is the energy associated with the movement of electrons. Both forms of energy involve the transfer or conversion of kinetic energy, making them appropriate choices for the description of "energy of movement".

Albert Einstein is the correct answer because he formulated the theory of relativity, which includes the principle of the conservation of energy. This principle states that energy cannot be created or destroyed, but only transformed from one form to another. Einstein's theory revolutionized our understanding of energy and its relationship to mass, leading to the famous equation E=mc^2, which shows the equivalence of energy and mass. Therefore, Einstein's contributions to physics solidified the concept of the conservation of energy.