Answer:

Explanation:
As we know that the rate of heat transfer due to temperature difference is given by the formula

here we know that

A = 4 m x 7 m
thickness = 30 cm
temperature difference is given as

now we have


Answer:
1. about 1.5 AU
2. about 5 AU
3. about 8 light-years
4. about 100,000 light-years
5. less than 0.01 AU
Explanation:
a. Mars is about 1.5 AU from the Sun.
b. Jupiter is about 5 AU from the Sun.
c. The star Sirius is about 8 light-years from the Sun.
d. The diameter of the Milky Way Galaxy is about 100,000 light-years.
e. The distance from Earth to the Moon is less than 0.01 AU.
Note: AU is an acronym for Astronomical Unit and it is a standard unit by astronomers to illustrate the distance between the planetary bodies found in the solar system.
Answer:
the number of grains in the ball is 274,848
Explanation:
Given that;
diameter = 0.5 mm
so radius r = 0.25 mm
first we determine the volume of the ball using the following equation;
V = 4/3×πr³
we substitute
V = 4/3×π(0.25)³
V = 0.06544 mm³
Now form table 1.1 "Grain sizes" a metal with grain size number of 12 has about 4,200,000 grains/mm³
so;
Number of grains N = 0.06544 × 4,200,000
N = 274,848 grains
Therefore, the number of grains in the ball is 274,848
The first thing you should know for this case is that density is defined as the quotient between mass and volume:
D = M / V
In addition, you should keep in mind the following conversion:
1Kg = 1000g
Substituting the values we have:
D = (23.0 * 1000) / (2920) = 7.88 g / cm ^ 3
answer
the density of the iron plate is 7.88 g / cm ^ 3