Answer:

Explanation:
The power needed to make the escalator working is obtained by means of the Work-Energy Theorem:




The mechanical efficiency of the escalator is:


Answer:
Please explain it in English so that i can help or you need someone else who can speak Vietnam
Answer:

Explanation:
Given
Airline flying at 34,000 ft.
Cabin pressurized to an altitude 8,000 ft.
We know that at standard condition ,density of air

We know that pressure difference
ΔP=ρ g ΔZ
Here ΔZ=34,000-8,000 ft
ΔZ=26,000 ft

ΔP=0.074 x 32.2 x 26,000

So pressure difference will be
.
It may be an engine cooler, or it may be for the boats speed
But I think it is for cooling the engine down