Explanation

When a projectile moves upward, gravity acts downward.

This opposes the vertical motion, so the vertical component of velocity decreases until it becomes zero at the highest point.

Explanation

A seismograph is an instrument used to detect and record earthquakes.

It consists of a mass attached to a fixed base

During an earthquake, the base moves and the mass does not.

Explanation

Ball falls 20m, so time taken is found using:

s = 1/2 gt²

20 = 1/2 × 10 × t²

t = 2s

Vertical velocity when it hits the ground:

v_y = gt = 10 × 2 = 20 m/s

Since it hits at 45°, v_x = v_y = 20 m/s

Explanation

Step 1: Parallel Combination

C_parallel = C + C = 2C

Step 2: Series with Third Capacitor

1/C_eq = 1/2C + 1/C

= (1/2C) + (2/2C)

= 3/2C

C_eq = 2C/3

Explanation

Impossible Situation:

Constant velocity requires zero acceleration (Newton’s First Law).

Variable acceleration would imply a changing net force, which must alter velocity (contradicting "constant velocity").

Possible Situations:

Zero velocity, non-zero acceleration:

Example: A ball at the top of its vertical toss (v=0, a=9.8 m/s² downward).

Velocity east, acceleration west:

Example: A car moving east while braking (deceleration acts west).

Velocity east, acceleration east:

Example: A car speeding up in the east direction.

Explanation

Ionization energy (potential) is measured in:

• Electron volts (eV) (for single atoms).
• Kilojoules per mole (kJ/mol) (for molar quantities).

Explanation

Water is called the "universal solvent".

Because it dissolves more substances (e.g., salts, sugars, acids) than any other liquid due to its polarity (uneven charge distribution).

Explanation

The approximate height of Earth's atmosphere is 6,200 miles (10,000 kilometers).

This is the approximate extent of the exosphere, the outermost layer of the atmosphere, which gradually merges with space. 

Explanation

A thermos flask is used to maintain the temperature of liquids, keeping hot things hot and cold things cold for extended periods.

It achieves this by minimizing heat transfer through a combination of insulation and a vacuum. 

Explanation

The main idea of the solar system was proposed by the Polish astronomer Nicolaus Copernicus (1473-1543).

who said that "the Sun is the centre of the Universe" and made the planets move around it in perfect circles

(in his book entitled, "On the Revolution of the Celestial Spheres", written in Latin and published in 1543)