Answer:
A measurement standard is a quantity that people agree to use as a comparison. Standards are important because they allow measurements to be compared even if different people in different parts of the world take them.
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Answers:
a) 
b) 
Explanation:
a) Since we are told the satellites circle the space station at constant speed, we can assume they follow a uniform circular motion and their tangential speeds
are given by:
(1)
Where:
is the angular frequency
is the radius of the orbit of each satellite
is the period of the orbit of each satellite
Isolating
:
(2)
Applying this equation to each satellite:
(3)
(4)
(5)
(6)
(7)
(8)
Ordering this periods from largest to smallest:

b) Acceleration
is defined as the variation of velocity in time:
(9)
Applying this equation to each satellite:
(10)
(11)
(12)
(13)
(14)
(15)
Ordering this acceerations from largest to smallest:

Answer:
V = 4.63 m/s
V = 11.31 m/s
Explanation:
Given,
The distance traveled by the bus, towards north, d = 2.5 km
= 2500 m
The time taken by the trip is, t = 9 min
= 540 s
The velocity of the bus,
V = d / t
= 2500 / 540
= 4.63 m/s
At another point, the bus travels at a constant speed of v = 18 m/s
Therefore the velocity becomes
V = (4.63 + 18)/2
= 11.31 m/s
Hence, the velocity of the bus, V = 11.31 m/s