Explanation

A weather balloon is not fully inflated on the ground because the air inside the balloon would expand and may burst as it rises.

The atmosphere is less dense at higher altitudes, so the pressure inside the balloon becomes greater than the pressure outside.

This causes the balloon to expand until it reaches its elastic limit and bursts.

Weather balloons typically burst at altitudes of over 15 miles (24.1 kilometers).

If a balloon were fully inflated on the ground, the gas would need to be vented out and wasted as it expands. 

Explanation

• Tungsten is very resistant to corrosion and has the highest melting point (melting point = 3695 K) and the highest tensile strength of any element.
• Tungsten is used for making bulb filaments of incandescent lamps because it has the highest melting point and does not melt even while it is glowing for long hours.

Explanation

• Television signals cannot be received ordinarily beyond a particular distance due to the curvature of the earth.

Key Points

• Signal waves travel in a straight line from the transmitting antenna to the receiving antenna. The signal transmitted from a TV tower cannot be received beyond a certain distance because the surface of the Earth is curved.
• This is due to, after going a certain distance the frequency of television signals decreases while their wavelength increases.
• Signal waves transmitted from a transmitter get absorbed or blocked by the curvature of Earth and are not received. 

Additional Information

• Signal:
  • Information converted in electrical form and suitable for transmission is called a signal.
  • Signals can be either analog or digital.

Explanation

The sun is visible a little before it rises and a little after it sets because of atmospheric refraction.

Refraction is the phenomenon that occurs when light changes direction as it passes from one transparent medium to another.

Explanation

Newton's Third Law of Motion states: "For every action, there is an equal and opposite reaction."

From this law, we can infer:

1. Statement 1: For every interaction, there is a pair of forces acting on the two interacting objects. (TRUE)
2. Statement 2: The magnitude of the force on the first object equals the magnitude of the force on the second object. (TRUE)
3. Statement 3: Forces always come in pairs - equal and opposite action-reaction force pairs. (TRUE)
4. Statement 4: Action and its reaction act on two same bodies. (FALSE - Action and reaction forces act on different bodies)
5. Statement 5: Action and its reaction act on two different bodies. (TRUE)

So, all statements except Statement 4 can be inferred from Newton's Third Law of Motion.

Explanation

Rainbows are caused by the refraction, reflection, and dispersion of light in water droplets in the atmosphere.

These processes break sunlight into its component colors.

Explanation

Electromagnetic waves, including light, travel at the same speed in a vacuum.

It is approximately 299,792 kilometers per second.

Explanation

• The acceleration due to gravity is 9.8 m/s² downward.
• This force acts on the ball throughout its motion.
• This pulling it back to the ground after it is thrown upwards.

Last updated 27-07-2026 by NA

Explanation

Objects that orbit around a planet are called satellites.

These can be natural, like the Moon, or artificial, like communication satellites.

Explanation

Systolic pressure, the top number in a blood pressure reading, represents the pressure in arteries when the heart beats.

A normal value is approximately 120 Torr (mmHg).