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1. a) Evaporation results in cooling as the liquid absorbs heat from its surroundings to regain the energy lost during evaporation. The absorption of heat from the surrounding makes the surrounding cool.
b) When the level of humidity is high the air already has a lot of water vapours. So it won't be easy to take more water vapours as there is no space present. Hence the rate decreases.
c) Sponge has very minute holes through which air is expelled out when applied pressure on it. But it is definately a solid as it has a defintie shape and volume.
2. Acceleration is deifined aa the rate of change of velocity. to derive the equation let us consider an object which has travelled displacement 's' in the time 't' under uniform acceleration 'a'. Let the initial and the final velocity be 'u' and 'v' respectively
- s = 1/2t (u+v) [the velocity relation] ...........(i)
v = u + at ............(ii)
Substitute (ii) in (i)
- s = 1/2t (u+u+at)
- s = 1/2t (2u + at)
- s = ut + 1/2 at²
Hope this helps :)