The unit of mass"kilogram" is a fundamental unit. why?​

kilogram is a fundamental unit because it is one of the 7 fundamental units that serve as a building block for derived units.

Explanation:

Fundamental units are used to measure fundamental quantities. They are fundamental units because they serve as a building block for derived units.

7 fundamental quantities and their corresponding units;

Length – meter

Mass – kilogram

Time - seconds

Temperature - Kelvin

Amount of substance - Moles  

Electric Current - Ampere  

Luminous intensity -  Candela

Thus, kilogram is a fundamental unit because it is one of the 7 fundamental units.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s