Answer:
C) 10 cm
Explanation:
We shall first calculate the focal length of the mirror.
object distance u = 20 cm ( negative )
Image distance v = 12 cm ( negative )
using mirror formula
1/ v + 1 /u = 1/ f
-1/12 - 1/ 20 =1/ f
f =- 7.5 cm
In the second case
u = - 30 cm
f = - 7.5 cm
i / v + 1 / u = 1 / f
1 / v - 1/30 = - 1/ 7.5
v = -10 cm
Answer is C that is 10 cm
Answer:
Thermal and internal energy is equal to the sum total kinetic energy possessed by the the molecules whereas the heat energy is the transfer of thermal energy from high temperature to low temperature.
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Orbital periods of stars in the Galaxy
1,000 milligrams = 1 gram
2,000 milligrams = 2 grams
3,000 milligrams = 3 grams
4,000 milligrams = 4 grams
Answer:
the diameter of the nozzle = 3 cm
Explanation:
let the diameter of nozzle be x cm.
then, area of cross-section at nozzle =
nozzle with a speed of 20 m/s, and speed of the water at the faucet is 5 m/s.
area of cross section at faucet = = 9π
now , area×velocity has to be constant (since area×velocity gives volume flow rate which should be same at both ends).
therefore
5×9π = 20×π×x^2/4
=>45 = 5×x^2
=>9 = x^2
=> x = 3 cm (as 3^2 =9)
therefore, the diameter of the nozzle = 3 cm