
- A

- B

- ✓

- Dnone of these





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$x = 3\,sin\, 20\pi t + 4\, cos\, 20\pi t$ ,
where $x$ is in $cms$ and $t$ is in $seconds$ . The amplitude is ..... $cm$
Statement $I:$ Acceleration due to earth's gravity decreases as you go 'up' or 'down' from earth's surface.
Statement $II:$ Acceleration due to earth's gravity is same at a height ' $h$ ' and depth ' $d$ ' from earth's surface, if $h = d$.
In the light of above statements, choose the most appropriate answer form the options given below
$(i)$ a body with large reflectivity is a poor emitter
$(ii)$ a brass tumbler feels much colder than a wooden tray on a chilly day
$(iii)$ the earth without its atmosphere would be inhospitably cold
$(iv)$ heating systems based on circulation of steam are more efficient in warming a building than those based on circulation of hot water