When a ray passes from air into glass the direction in which the light ray is travelling changes. The light ray appears to bend as it as it passes through the surface of the glass. When a light ray passes from air into water a similar thing occurs: the light ray is bent as it strikes the surface of the water.
B. Warm air rises and takes heat with it; eventually it cools and sinks.
Explanation:
Warm air rising and taking heat with it which eventually cools and sinks describes a typical convection current. This is not radiation
Convection and radiation are both forms of heat transfer alongside conduction.
Radiation is the only form of heat transfer that does not involve the use of a medium or particles.
Air is a medium and it flouts the concept of heat transfer by radiation.
Convection is mostly taking place in fluids especially liquid and gas.
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Convection brainly.com/question/377220?source=aid8168908
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The only vertical forces are weight and normal force, and they balance since the surface is horizontal. The horizontal forces are the applied force (uppercase F) in the direction the block slides and the frictional force (lowercase f) in the opposite direction.
Apply Newton's 2nd Law in the horizontal direction:
ΣF = ma
F - f = ma
where f = µmg
F - µmg = ma
F = m(a +µg)
F = (20 kg)(1.4 m/s² + 0.28(9.8 m/s²)
F = 83 N
If 
and 
are perpendicular, then their dot product is zero. This means
Solving for n is trivial; it follows that n = 3.
