variation

The intensity of light is measured in Lux. It is found that the intensity of light varies as the inverse square of the distance between light source and point of measurement.
if at 10 meters, the intensity is 100 lux, what is the intensity of the light at 15 meter distance.

math for fun

 

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2-variations

The pressure of gas under constant heat condition is found to vary inversely with the volume raised to the power of γ, where γ is the ratio of specific heat of the gas under constant pressure to constant volume, and is found to be 1.14. A student observes that a certain gas occupies a volume of 22.4 litres under 3 kg /cm² pressure. What will be the pressure of gas if the same quantity of gas is reduced to 11.2 litres?

variation

For a free falling body, the instantaneous velocity is proportional to square of time taken. In 3.3 sec. the velocity of the body is 100 m/s. What will be the velocity after 10 sec.?