Explanation

According to the kinetic molecular theory, the pressure exerted by a gas is caused by the bombardment of gas molecules on the walls of the container.

The gas molecules are in constant motion, colliding with each other and the container walls, resulting in a force exerted on the walls.

This force is what we experience as pressure.

Explanation

The critical velocity (vc) is the minimum velocity an object must have to orbit the Earth without falling to the ground.

It is given by the formula:

vc = √(gR)

where:

• g is the acceleration due to gravity (approximately 9.8 m/s²)
• R is the radius of the Earth (approximately 6,371 kilometers)

Explanation

A Bunsen burner is made more stable by increasing its base area, which lowers its center of gravity and makes it less likely to tip over.

This is a common design principle in engineering, where a wider base provides greater stability.

Explanation

• Gravitational potential is always negative, because it is defined as the work done per unit mass to bring an object from infinity to a given point in a gravitational field.
• Since the force of gravity is attractive, work must be done to move an object against the force of gravity, and this work is negative.

Explanation

 non-magnetic materials are examples

• Rubber
• plastic
• stainless steel
• feather
• paper
• mica
• gold
• Silver
• leather***

  ND18-1-2023

Explanation

 Velocity is a vector quantity

Because it requires both magnitude (speed) and direction to be fully defined.

In contrast, speed is a scalar quantity as it only has magnitude.

Explanation

Resistivity after cutting a wire in half:

Resistivity 𝜌 is a material property, independent of shape, size, or length.

When a wire is cut, resistance changes, but resistivity remains the same.

Explanation

 Those substances through which electric current cannot pass are called insulators.

Insulators have very high electrical resistance

. For example, wood, rubber, glass, paper, plastic and wax are insulators of electricity.

Insulators cannot conduct electricity due to absence of free electrons in them.

Explanation

The speed of sound in air is affected by two main factors:

1. Temperature: As temperature increases, the speed of sound increases. This is because warmer air is less dense, allowing sound waves to travel faster.
2. Humidity: As humidity increases, the speed of sound decreases slightly. This is because water vapor in the air adds mass to the air molecules, making them slightly heavier and slower.

Explanation

Latent heat of vaporization is the energy required to change a liquid into a gas (or vice versa) without changing its temperature.

Latent heat of fusion is the energy required to change a solid into a liquid (or vice versa) without changing its temperature.