Explanation

The gravitational field of Earth is a vector field that points towards the center of the Earth.

It representing the direction of the gravitational force that the Earth exerts on objects near its surface.

This means that the gravitational field is directed towards the Earth, pulling objects towards its center.

Explanation

The motion of a falling ball towards Earth is due to the gravitational force.

Gravitational force is the force that attracts the ball towards the Earth, causing it to accelerate downwards.

Explanation

Nuclear energy is the energy released from the nucleus of an atom, either through fission (splitting of atoms) or fusion (combination of atoms).

This energy is released in the form of heat and radiation, and is harnessed in nuclear power plants to generate electricity.

Key Points:

• Solar energy is energy from the sun
• Geothermal energy is energy from the Earth's internal heat
• Tidal energy is energy from ocean tides

Explanation

The kinetic energy (K.E) of an object is calculated as:

• K.E = (1/2) x mass x velocity^2
• = (1/2) x 1 kg x (1 m/s)^2
• = 0.5 Joule
• = 1/2 Joule

So, the kinetic energy of the body is 1/2 Joule or 0.5 Joule.

Explanation

A communication satellite in a geostationary orbit completes one revolution around the Earth in 24 hours.

This is the same amount of time it takes the Earth to rotate once on its axis.

Explanation

Newton is a unit of force, not pressure.

The units of pressure are:

• Pascal (Pa) is the SI unit of pressure.
• Bar is a common unit of pressure, equal to 100,000 Pa.
• Atmosphere (atm) is a unit of pressure, equal to 101,325 Pa.

Explanation

To find the acceleration of the sledge, we can use Newton's second law of motion: F = ma, where F is the net force acting on the sledge, m is its mass, and a is its acceleration.

First, we need to find the net force acting on the sledge. The force applied by the man is 60 N, and the force of friction is 20 N, so the net force is:

F = 60 N - 20 N = 40 N

Next, we can plug in the values to Newton's second law:

40 N = (25 kg) × a

To find the acceleration, we can divide both sides by the mass:

a = 40 N / 25 kg = 1.6 ms^-2

Therefore, the acceleration of the sledge is 1.6 ms^-2.

Explanation

Condensing is the process by which a gas changes state to become a liquid.

This occurs when the temperature and pressure of the gas are reduced to the point where the molecules slow down and come together to form a liquid.

Key Points:

• Melting is the process where a solid becomes a liquid.
• Freezing is the process where a liquid becomes a solid.
• Boiling is the process where a liquid becomes a gas.

Explanation

Vector quantities are physical quantities that have both magnitude (amount or size) and direction.

Examples of vector quantities include:

• Displacement
• Velocity
• Acceleration
• Force
• Momentum

Explanation

The velocity of a satellite is independent of its mass.

According to Kepler's laws, velocity is determined by the orbit's semi-major axis and the central body's gravitational constant (G), not by the satellite's mass.