Explanation

• In a longitudinal wave, a rarefaction is a region where the particles are furthest apart.
• This is in contrast to a compression, which is a region where the particles are closest together.

Explanation

• A kaleidoscope contains several mirrors placed at an angle to each other, usually 60 degrees.
• This allows multiple reflections to be created of the objects inside the kaleidoscope.

Explanation

• Grease is a lubricant that can be used to reduce friction between moving parts of machines.
• It helps to reduce wear and tear, prevent overheating, and allow parts to move smoothly.

Explanation

To find the speed, we can use the formula:

Speed = Distance / Time

Given:

Distance = 150 meters

Time = 5 seconds

Speed = 150 / 5

Speed = 30 m/s

So, the cycling speed of the girl is 30 meters per second.

Explanation

• An object moving along a circular path is experiencing a change in direction, which means it is constantly accelerating.
• According to Newton's first law of motion, an object in motion will remain in motion with a constant velocity unless acted upon by an external force.
• In the case of an object moving in a circular path, the force of centripetal acceleration is acting on the object, causing it to change direction and accelerate towards the center of the circle.
• Therefore, the object is not in equilibrium.

Explanation

Fringe spacing in a double-slit experiment is inversely proportional to slit spacing (Δy ∝ 1/d).

So, doubling the slit spacing results in the fringe spacing being halved.

Explanation

The average daily food intake provides about 8,000–10,000 kJ, similar to the energy in 0.33 liters of petrol.

This comparison helps relate human energy needs to fuel energy.

Explanation

Lenz's law states that the direction of induced current in a closed loop is such that it opposes the change in magnetic flux that produced it.

This means that if the magnetic field through a loop increases, the induced current will flow in a direction that creates a magnetic field opposing that increase, and vice versa.

Explanation

Relative permittivity is the ratio of a medium's is defined by:

1. The ratio of the electric field in vacuum to the electric field in the medium

and

2. The ratio of the capacitance with the medium to the capacitance with air

Explanation

• A black hole is a region of space where matter has collapsed in on itself.
• It creating an incredibly dense and gravitational field so strong that not even light can escape.