I want to say its cooled by reflection because of the foil, sun reflects off of the foil back into the atmosphere. I don't think it's conduction because I have the foil on my windows and it's never warm to the touch. it's not a liquid so I don't believe it's convection. The foil reflects the radiation so I don't think it's b, c or d. so I wanna say A but I'm not 100% sure

Since the diameter of helium atom is approximately
, therefore the diameter of helium atom in nano meter,

Physical change = changes the physical properties (more commonly known as it's look)
Chemical change = changes the chemical properties into an entire new chemical form
Examples of physical change would be melting ice cubes or sugar cubes.
Examples of chemical change would be cooking eggs or burning paper because you're changing its chemical properties.
Answer:
a) 2.43 m/s
b) 4.83 m/s
c) 0.023 m/s²
Explanation:
a) Both cars cover a distance of 510 m in 210 s. Since car A has no acceleration
Speed = Distance / Time

Velocity of car A is 2.43 m/s
t = Time taken = 210 seconds
u = Initial velocity
v = Final velocity
s = Displacement = 510 m
a = Acceleration
c)

Acceleration of car B is 0.023 m/s²
b)

Final velocity of car B is 4.83 m/s
Weight and mass are used synonymously on earth because the value of g is constant on the earth because the weight of a body is the amount of force exerted by the Earths gravity on an object of finite mass. And, the mass of an object gives the amount of matter in the body and is measured in kilograms.