Answer:
I think the answer would be British Thermal Unit
Explanation:
It equals one degree Fahrenheit and the equation for it is 1.055 × 103 joules.
Mechanical Wave cannot travel in space vaccumes, which would be considered "Empty Space" in your situation.
Answer:

Explanation:
The figure of the problem is included below as attachment. The equations of equilibrium are presented below:



The system of equations are:


![N_{1} \cdot [(0.75\,m)-0.2\cdot (0.35\,m)] - N_{2}\cdot (1.25\,m) = 0](https://tex.z-dn.net/?f=N_%7B1%7D%20%5Ccdot%20%5B%280.75%5C%2Cm%29-0.2%5Ccdot%20%280.35%5C%2Cm%29%5D%20-%20N_%7B2%7D%5Ccdot%20%281.25%5C%2Cm%29%20%3D%200)
The solution of the system is:
,
and 
The shortest time to reach a speed of 80 km/h is:

