4. What is the role of a compressor in an air conditioner?
O It exchanges warm air for cold air and blows it into the room.
O It increases the pressure and temperature of the refrigerant.
O It absorbs heat from the room and blows it outside.

b

Explanation:

it compresses hot air turning into cool air almost like a reverse tornado

It increases the pressure and temperature of the refrigerant.

Explanation:

The purpose of the compressor is to circulate the refrigerant in the system under pressure, this concentrates the heat it contains. At the compressor, the low pressure gas is changed to high pressure gas.

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