Ch 10 covers gravitation from Newton's universal law to everyday phenomena like weight, free fall, floating, and sinking. Students learn about mass vs weight, thrust, pressure, buoyancy, and Archimedes' principle.
Every object attracts every other object with a force F = Gm₁m₂/r² where G = 6.67 × 10⁻¹¹ N m²/kg². Force is proportional to the product of masses and inversely proportional to the square of distance. Free fall: when only gravity acts on an object, a = g = 9.8 m/s² (use equations of motion with a = g).
Mass: amount of matter (kg), constant everywhere. Weight: gravitational force on an object, W = mg (N), varies with location. On the moon, g = 1.63 m/s², so weight is ~1/6 of earth weight. Buoyant force: upward force by a fluid on an immersed object. Archimedes' principle: buoyant force = weight of fluid displaced.
Download: https://ncert.nic.in/textbook/pdf/iesc110.pdf | Complete book: https://ncert.nic.in/textbook/pdf/iesc1ps.zip
Astronauts in orbit are in a state of continuous free fall towards Earth (but they move forward fast enough to keep missing it). Since both the astronaut and the spacecraft fall at the same rate, there is no normal force — and this absence of normal force creates the sensation of weightlessness.
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