MCQ (Solution) - Pressure, Winds, Storms, and Cyclones | Science Curiosity Class 8 - New NCERT PDF Download

Answer: Option B
Solution:

• Pressure equals force per unit area; the same weight spread over a larger area creates less pressure on the shoulders, improving comfort.
• This is why cloth pads under head loads or broad bucket handles also reduce discomfort.
• Why others are incorrect: Gravity and mass do not change (A, C), and friction with clothes (D) is not the reason for reduced pressure.

Answer: Option B
Solution:

• Pressure is force per unit area; its SI unit is N/m², called the pascal (Pa).
• Millibar (mb) and hectopascal (hPa) are common for atmospheric pressure, both equal to 100Pa.
• Why others are incorrect: N/m (A) is not pressure; kg/m² (C) is not an SI unit for pressure; N·m (D) is work/energy (joule).

Answer: Option B
Solution:

• Liquid pressure at a depth depends primarily on the height of the liquid column above that point; greater height means greater pressure.
• This explains why overhead tanks at higher levels give stronger tap flow below.
• Why others are incorrect: Area or volume (A, C) are not the determining factors here; pressure never becomes zero in a filled column (D).

Answer: Option D
Solution:

• Liquid pressure acts in all directions—downward, sideways, and even upward—on container surfaces at a given depth.
• Equal-height side holes spurt water with similar streams, demonstrating side pressure.
• Why others are incorrect: A, B, C are incomplete and ignore directional nature of fluid pressure.

Answer: Option C
Solution:

• Water pressure increases with depth, so the base experiences the greatest lateral pressure and must be thicker to resist it.
• Structural stability also benefits from a wider base.
• Why others are incorrect: A is unrelated; B is false (pressure is greatest at bottom); D contradicts the need for strength.

Answer: Option C
Solution:

• Atmospheric pressure acts omnidirectionally; we are not crushed because internal fluids and gases exert an equal counterpressure.
• This also explains why suction cups stick when internal air is expelled, creating a pressure difference.
• Why others are incorrect: A underestimates its magnitude; B is incorrect—pressure is not only downward; D is unscientific.

Answer: Option B
Solution:

• Winds are driven by pressure gradients: air moves from high to low pressure, which explains sea breezes (day) and land breezes (night).
• Temperature differences often create these pressure differences.
• Why others are incorrect: A reverses the direction; C ignores pressure’s role; D is not a universal rule.

Answer: Option B
Solution:

• High-speed winds are associated with lower pressure regions, which can create roof-lifting effects due to pressure differences.
• Blowing between two balloons makes them move closer for the same reason—reduced pressure in the fast airflow region.
• Why others are incorrect: A and C contradict observed phenomena; D ignores the fundamental wind–pressure link.

Answer: Option B
Solution:

• Fast winds over roofs lower outside pressure; opening passages reduces pressure differences, lowering the risk of roofs being blown off.
• This minimizes damaging uplift forces on structures.
• Why others are incorrect: A is irrelevant; C can worsen differential; D is not feasible in strong storms.

Answer: Option B
Solution:

• When moist air rises and water vapor condenses into droplets, latent heat is released, warming and accelerating the ascending air, deepening low pressure.
• This positive feedback powers cyclones over warm oceans.
• Why others are incorrect: A and C are not cyclone drivers; D removes heat locally but the key intensification comes from heat release during condensation.

Answer: Option B
Solution:

• The eye is the calm, clear region of lowest pressure; destructive winds and heavy rain encircle it in the eyewall.
• As cyclones make landfall, they weaken due to reduced moisture supply.
• Why others are incorrect: A confuses eye with eyewall; C is not a defining feature; D contradicts cyclone structure.

Answer: Option B
Solution:

• Thunderstorms need warm moist air and strong vertical motions; rising air cools to condense into droplets/ice, producing clouds, rain, lightning, and thunder.
• Charge separation occurs via collisions of droplets and ice, enabling lightning discharges.
• Why others are incorrect: A and C invert the thermodynamics; D ignores moisture and charging processes.

Answer: Option C
Solution:

• Pressing the cup expels most air beneath it, lowering internal pressure; higher external atmospheric pressure presses it tightly to the surface.
• Removing it requires overcoming this pressure difference.
• Why others are incorrect: A and D are irrelevant; B reverses direction of forces.

Answer: Option C
Solution:

• Minimize being the tallest object and reduce contact with ground; avoid conductors like water and metal; vehicles provide relative safety.
• Buildings may be protected with lightning conductors to safely channel charges to ground.
• Why others are incorrect: A and D increase strike risk; B increases ground current exposure.

Answer: Option C
Solution:

• Pressure at a point in a static liquid depends on the vertical height of the liquid column above that point (hydrostatic head), not on the tank’s size or color.
• Greater height produces stronger flow at lower floors.
• Why others are incorrect: A and B don’t change head at the outlet; D has no effect on static pressure.