Explanation

1 calorie = 4.2 joules (exact value is 4.184 J), so 1000 cal = 4184 J.

1 kilocalorie (kcal) = 4184 joules, commonly used in food energy.

Explanation

• As gas particles move faster, they exert a greater force on the container walls, resulting in increased pressure.
• This relationship is described by the kinetic molecular theory, which states that the pressure of a gas is directly proportional to the square of its velocity.

Explanation

• Dust and gas in the interstellar medium (ISM) can absorb and scatter starlight.
• It leading to a reduction in the brightness of stars as seen from Earth.
• This is known as interstellar extinction.

Explanation

• The movement of free electrons is defined as electric current, which is the flow of electrons through a conductor, such as a wire.
• Electric charge refers to the property of matter, electric field is the force that surrounds charged particles, and electric potential is the potential energy per unit charge.

Explanation

• The speed of sound in diamond is approximately 12,000 meters per second (m/s).
• It is one of the fastest speeds of sound among all materials.

The speeds of sound in different materials:

• Air: 343 m/s
• Water: 1433 m/s
• Wood: 3300-3600 m/s
• Brick: 4176 m/s
• Steel: 6100 m/s
• Diamond: 12000 m/s

Explanation

• The atomic number (Z) is the number of protons in the nucleus of an atom.
• In this case, the atomic number (Z) is 16, which means the number of protons is 16.

Explanation

• When light hits a shiny surface, it bounces back without being absorbed or passing through the surface.
• This phenomenon is called reflection.
• The angle of incidence (the angle at which light hits the surface) is equal to the angle of reflection (the angle at which light bounces back).

Explanation

Gears can:

• Change speed: Gears can increase or decrease
• Change direction: Gears can change the direction of rotation
• Change force: Gears can increase or decrease the force

However, gears cannot change the fulcrum, which is the pivot point or axis of rotation.

Explanation

• When oil is burnt, it undergoes combustion, a chemical reaction that releases energy in the form of heat and light.
• It produces carbon dioxide (CO2) and water (H2O) as byproducts.
• The energy released can be used to power vehicles, generate electricity, or provide warmth.

Explanation

• Photosynthesis is the process by which plants, algae, and some bacteria.
• It convert light energy from the sun into chemical energy in the form of glucose (sugar), using carbon dioxide and water as reactants.