Scientist often use which are programs that combine what is known about atmospheric circulation

General circulation model.

Explanation:

A general circulation model (GCM) is a type of climate model that employs a mathematical model of the general circulation of a planetary atmosphere or ocean. GCM uses the Navier–Stokes equations on a rotating sphere with thermodynamic terms for various energy sources (radiation, latent heat). These equations are the basic equations for computer programs used to simulate the Earth's atmosphere or oceans.

The missing word is Computer Based Climate Models.

Explanation:

Computer-Based Climate Models are simply software which uses data collected about atmospheric conditions, air circulation, ocean circulation, interactions between weather elements and various climatic cycles to predict climate and weather.

These are often used by Meteorologists. Meteorologists are simply scientists who study and predict climate and weather.

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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

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.