Pressure, Winds, Storms and Cyclones

Your friend on the 1st floor gets the more powerful stream.

Water pressure depends only on the HEIGHT of the water column above the point where you're measuring it. The 1st floor is FARTHER below the tank than the 2nd floor is, so the column of water above the 1st-floor tap is TALLER — giving it more pressure and a stronger stream. The 2nd floor, being closer to the tank, has a shorter water column above it, so weaker pressure.

(d) Equal in all three vessels.

Connected vessels always settle to the SAME water level, no matter their shape or width — liquid pressure at any depth depends only on the HEIGHT of liquid above that point. If one vessel had a higher level, the extra height there would push water sideways into the others until all levels match. This is the same idea used to make sure taps in a building all get water at the right level!

(c) M will stick, N will not stick.

A sucker sticks because pressing it out pushes almost all the air out from under it, so the outside atmospheric pressure holds it firmly against the surface. On a SMOOTH surface, the sucker's rim seals tightly, keeping that air out — so it sticks. On a ROUGH surface, tiny gaps and bumps let air leak back in underneath, so the pressure can't stay low, and the sucker won't stick.

(a) Increase the height H.

Water pressure depends only on the HEIGHT of the water column, not on how much water the tank can hold (its capacity/width doesn't matter). So options (c) and (d) — changing the tank's capacity while keeping H the same — won't change the pressure at all. Only raising the tank higher increases the pressure at the ground floor.

(b) P_A = P_B, but F_A < F_B.

Since both vessels are filled to the SAME height, the PRESSURE at the bottom is equal in both (pressure only depends on height, not on the container's width) — so P_A = P_B. But FORCE = Pressure × Area, and vessel B has a wider base (bigger area) than narrow vessel A. Same pressure over a bigger area means a bigger total force, so F_A < F_B.

Boat B feels more pressure, by 100 N/m².

His weight is the SAME either way, but lying down spreads that weight over his WHOLE body (large area = low pressure), while standing puts all his weight on just his two feet (small area = high pressure) — so standing makes him sink in more!

No. Lightning only happens because air is normally an INSULATOR, letting charge build up until it suddenly breaks through. If air conducted electricity easily, charges would just leak away gradually as they formed — no big build-up, no dramatic flash.

Yes, equally! Water pressure depends only on the HEIGHT of the water column above the balloon, not on the shape or size of the balloon — since both are fed from the same height, both feel the same pressure.

Over warm ocean water, rising moist air releases heat as it condenses into rain — that extra heat makes the air rise even faster, dropping the pressure further. Surrounding air rushes in, and Earth's rotation makes the whole system spin, building an organized storm with a calm "eye" and powerful winds around it — a cyclone.

On a summer afternoon, the land has been heating up in the sun all day, so it gets hotter than the sea. Warm air over the land rises, creating LOW pressure there, and cooler, higher-pressure air from over the sea rushes in to fill the gap — this is the sea breeze, blowing FROM the sea TOWARDS the land.

Trees bend in the direction the wind is pushing them — so they lean away from the sea and towards the land. That means the side the trees are leaning AWAY FROM is the sea, and the side they are leaning TOWARDS is the land. (The textbook figure shows the coastal trees tilted from the water's edge inland — so whichever side the tree-tops point towards is land, and the side they point away from, where the wind is coming from, is the sea. Patto's tip: always match the lean direction of the trees to the sea-breeze direction to answer this style of question, since the exact print orientation of A and B can vary between copies of the figure!)

You'll see the inflated balloon slowly shrink while the empty one slowly inflates, until after a while both balloons are almost the same size and the change stops.

Why: the inflated balloon starts at HIGH pressure and the empty one is at LOW pressure — air always moves from high pressure to low pressure. The flow continues until the pressure in both balloons becomes equal, which is when they reach almost the same size and the airflow stops.

A thunderstorm is a storm that comes with both lightning and thunder.

In short: a storm that is accompanied by lightning and thunder is called a thunderstorm. It needs moisture and strong winds to form.

A sudden, huge flow of charge rushes through the air — that bright flash is lightning. It can happen within a single cloud, between two clouds, or between a cloud and the ground. The rapid heating of the air around it makes the air expand suddenly, producing the loud sound of thunder.

Holes let wind pass THROUGH the banner instead of pushing against one big solid surface. This reduces the pressure difference and force on the banner — same idea as keeping windows open during a storm — so it's less likely to tear or blow away.

Measures taken by government & communities: Early warnings and path-tracking by the India Meteorological Department (IMD); mass evacuation of coastal villages to cyclone shelters before landfall; deployment of the National Disaster Response Force (NDRF) for rescue and relief; and quick restoration drives for power and roads after the storm.

Two suggestions we could make to the local government:

You could look up IMD data or news reports on thunderstorm frequency for a few states, and record it in a simple table like this:

Why the difference: Thunderstorms need both moisture AND strong rising warm air. Eastern and north-eastern India sit close to the Bay of Bengal and get very moist, warm air, so they see stronger and more frequent thunderstorms. Drier north-western regions have far less moisture in the air, so thunderstorms are much less common there — even though it can still get very hot.

(b) pascal (Pa)

(c) sea to land, during the day

High-speed wind blowing over a roof creates a low-pressure zone above it. If doors and windows stay shut, the normal (higher) pressure trapped inside the house pushes UP against the roof from below, and if that pressure difference is big enough, it can blow the roof off. Keeping windows open lets the wind flow through the house, equalizing pressure inside and outside, reducing the risk of the roof being blown away.

(a) Stay updated with IMD alerts, keep an emergency kit ready, and move to a designated cyclone shelter when instructed.

(b) The eye of a cyclone is CALM, so people might think the storm has passed and go outside — but the fierce winds and rain return suddenly as the other side of the storm arrives.

(c) Storm surge (a 3–12 m wall of seawater flooding the coast) and seawater contaminating drinking water/farmland — beyond the wind damage itself.