Explanation

Attrition is the process where rocks and pebbles grind against each other, causing them to wear down.

It occurs mainly in rivers or along the coast due to movement and collision.

Explanation

According to the Big Bang Theory, all the matter and energy in the universe was initially concentrated in a single point with nearly infinite density.

This point was extremely small, about one nanometer in size, before the universe began expanding.

According to Big Bang Theory, the Universe began about 10-20 billion years ago.

Explanation

According to the law of conservation of energy, the total energy in the universe remains constant.

Energy can change forms (e.g., from kinetic to potential), but the total amount doesn't decrease or increase.

Explanation

Explanation

Gear is: wheel or cylinder

Pulley is: a wheel with a grooved rim

Explanation

Two or more forces acting on the same point at the same. time are called concurrent forces.

While

A concurrent coplanar force system is a system of two or more forces whose lines of action intersect at a common point.

Explanation

When an elevator accelerates downward, the normal force (apparent weight) decreases.

Thus, the person feels lighter than their actual weight.

Explanation

The dielectric constant of water at around 18°C is approximately 80.

This high value makes water an excellent polar solvent for ionic and polar compounds.

Explanation

The mesosphere is the coldest layer of the atmosphere, with temperatures dropping as low as -90°C.

It lies above the stratosphere and below the thermosphere.

Explanation

A rectifier is an electrical device that converts Alternating Current (AC) into Direct Current (DC).

It works by allowing current to flow only in one direction using diodes.