Answer:
43.7 °C
Explanation:
= Coefficient of linear expansion of brass = 
= Coefficient of linear expansion of steel = 
= Initial length of brass = 31 cm
= Initial length of steel = 11 m
= Total change in length = 3 mm
Total change in length would be


The final temperature is 43.7 °C
The angular speed is defined as:
<h2> ω=

</h2>
where



Answer:
A) 80 N
Explanation:
The closer the particles get, the stronger the Coulomb force, which elongates choices C and D. The Coulomb force is inversely proportional to the distance squared. If the distance is cut in half, the force is multiplied by the reciprocal of (1/2)^2, which is 4. Multiplying it out, 20 times 4 is 80 N.
It’s solved by using a pretty standard formula for efficiency.