NCERT Solutions for Class 8th Science Chapter 6 Chapter opening text · 6.1 Pressure — In-text Questions

Because moving air pushes on them — the wind exerts a force on every surface it meets.

A leaf lying on the ground has a large surface for its very small weight. When wind blows across it, the air pushes on that surface, and even a modest push is enough to lift the leaf and carry it along. A tree is far heavier, but its leaves and branches present a very large area to the wind, so the total force on the crown becomes large enough to bend the trunk.

Yes. Moving air exerts a force on whatever it strikes, and that force is what raises the leaves and bends the trees.

We recognise a force by what it does — it can make a resting object move, change its speed or direction, or change its shape. The wind does all of these: a still leaf starts moving, a swaying branch changes direction, a straight trunk bends. Slamming doors, rattling windows and fluttering clothes are the same force showing itself in other ways.

Yes — not to the weight of the bag, but to the pressure that weight produces on the shoulders.

Megha's and Pawan's bags are equally heavy, so gravity pulls both down with the same force. But that force is passed to the shoulders through the straps. Pawan's narrow straps deliver the whole force over a small area of skin, while Megha's broad straps spread the same force over a much larger area. Since pressure is force divided by area, the pressure under the narrow straps is much greater, and it is high pressure on the skin that hurts.