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

• An electric motor converts electrical energy into mechanical energy, producing motion or rotation.
• It uses electromagnetic forces to generate torque, which drives a shaft or other mechanical components.

Explanation

When light strikes an opaque object, the light is blocked, thus a Shadow is formed on the opposite side of the object.

Explanation

• A thermal conductor is a material that allows heat energy to flow through it easily.
• Such as metals like copper, aluminum, and iron.

Explanation

By joining two hemispheres along their bases we have a sphere.

Total surface area of sphere = 4×πr2

Explanation

• Fleming's left-hand rule correlates to current, magnetic field and direction of force on a conductor.
• This rule states that if the thumb, forefinger and middle finger of the left hand are stretched to be perpendicular to each other, and if the forefinger represents the direction of the magnetic field, the middle finger represents the direction of the current, then the thumb represents the direction of force.
  

Explanation

Explanation

• Kinetic friction (fk) is the frictional force that acts on an object when it is already moving, whereas static friction (fs) is the frictional force that prevents an object from moving when a force is applied to it.
• The relationship between kinetic friction and static friction is: fk < fs
• Kinetic friction is always less than static friction because it takes less force to keep an object moving than to start it moving from rest.
• This is because the surfaces in contact have already overcome the initial resistance to motion when the object is moving, making it easier to maintain motion.

Explanation

• The energy received from the sun on earth is proportional to the square of the temperature of the sun (Stefan-Boltzmann law). If the temperature of the sun is doubled, the energy received on earth will increase by a factor of 2^2 = 4. 
• However, since the energy is also proportional to the square of the radius of the sun, and the radius remains constant, the total increase in energy received is 4^2 = 16.
• So, if the temperature of the sun is doubled, the rate of energy received on earth will be increased by a factor of 16.