Answer:
Explanation:
Energy of gamma rays due to ore decay is
Energy of gamma ray produced in seconds is
Activity
Total energy of gamma ray produced in second is
E-energy of gamma ray produced in an hour is
Gamma ray energy absorbed by meat = 30% (in 1 hour) of E is 0.3E
Dose required to kill pathogen = 4000Gy=4000J/kg
The kilogram of meat that can be produced per hour is
The meat that can be produced =
Since the continents are moving ever so slightly over the years, in couple million years they could all connect again like Pangaea.
The relationship between resistance R and resistivity
is
(1)
where L is the length of the wire and A is the cross-sectional area.
In our problem, the radius of the wire is half the diameter: r=1 mm=0.001 m, so the cross-sectional area is
The length of the wire is L=20 m and the resistance is
.
By re-arranging equation (1), we can find the resistivity of the wire:
Answer:
.c. −160°C
Explanation:
In the whole process one kg of water at 0°C loses heat to form one kg of ice and heat lost by them is taken up by ice at −160°C . Now see whether heat lost is equal to heat gained or not.
heat lost by 1 kg of water at 0°C
= mass x latent heat
= 1 x 80000 cals
= 80000 cals
heat gained by ice at −160°C to form ice at 0°C
= mass x specific heat of ice x rise in temperature
= 1 x .5 x 1000 x 160
= 80000 cals
so , heat lost = heat gained.
Gravity is often assumed to be the same everywhere on Earth, but it varies because the planet is not perfectly spherical or uniformly dense. In addition, gravity is weaker at the equator due to centrifugal forces produced by the planet's rotation
