Answer:
Lack of proper roof ventilation
Explanation:
The icicles hanging off the eaves of a roof are due to lack of proper roof ventilation. This means after snowfalls the attic of the roof receives warm air which melts the snow above. This is caused because the upper part of roof is above 32⁰C (which melts the snow) and lower part of your roof is at a lower temperature which refreezes the snow dripping down to form icicles.
Hydrogen is the original fuel that keeps a star "burning" by nuclear fusion.
No hydrogen and the star will die unless it can start use helium to produce energy.
Answer:
d) is the same as when it started from rest
Explanation:
using equation of motion
v = u + at
second law of momentum defines
F = ma
a = F /m
the equation becomes
v = u + (F/m)t
from hear
since v is directly proportional to the force and the force remain the same, the increase in the cart speed will also remain the same.
Explanation:
mass of copper block = 0.3 kg at 77 K or -196 °C
Let mass of water taken be m ( maximum) , in this case we will have mixture of water and copper block at 0°C finally.
Heat gained by copper block
= msΔt
.3 x 196 x 385 J
heat lost by water to lower its temp fro 50°C to 0°C
= m x 4186 x 50
Heat lost = heat gained
m x 4186 x 50 = .3 x 196 x 385
m = 108.16 gm
Let mass of water taken be m ( minimum ) , in this case we will have mixture of ice and copper block at 0°C finally.
heat lost by water to lower its temp fro 50°C to 0°C
= m x 4186 x 50
heat lost by water to lower its temp from 0°C to 0°C ice
= m x latent heat of fusion
m x 3.35 x 10⁵
Total heat lost
= m x 3.35 x 10⁵ + m x 4186 x 50
= 544300 m
Heat gained by copper block
= msΔt
.3 x 196 x 385 J
Heat lost = heat gained
544300 m = .3 x 196 x 385 J
m = 41.6 gm