Answer:It started at 20°C, the bras and the iron must b cooled at -150°C.
Explanation:
The formular for linear expansion is given by:
L = Lo + Lo&◇T
Where L = linear dimensions)diameter) after temperature change.
Lo=Original linear dimension
&= Coefficient of thermal expansion for the material.
◇T=Change in temperature.
At some temperature,L(brass)=L(iron)
Lo + Lo&◇T = Lo + Lo&◇T
8.753cm + 8.753cm×(8.7×10^-6C^-1)×◇T=8.753cm+ 8.753cm ×(12.0×10^-6C^-1)×◇T
8.753+(1.636×10^-4)◇T= 8.753+(1.049×10^-4C^-1)◇T
5.87 × 10^-5◇T= 0.010
◇T= 0.010/(5.87×10^-5)
◇T= 170°C
◇T=T1-T2
T= (20 - 170)°C
T= -150°C
3.
If the reaction forms a new substance it's a chemical reaction.
Answer:
Ionic compound
Explanation:
Barium Chloride is an ionic compound of barium and chlorine.
Barium is a metal with two valence electrons while chlorine is a non metal with seven valence electrons.
Barium will require two atoms of chlorine to form Barium chloride.
The reaction can be demonsated in the equation below.
Ba2+ + Cl- -----------> BaCl2
In this type of bond, Barium uses its 2 valence electrons to form an ionic bond with 7 valence electrons of chlorine. Chlorine will require its own two atoms to form this type of bond with Barium.
Cl -Ba-Cl = BaCl2
Answer: Yes.
Explanation: Work in physics is defined as a force causing the movement—or displacement—of an object. In this case your eyes blinking, even though it was a very quick movement that didn't require much effort or energy, is still an example of your body at work.