21. light changes its direction when travelling through a new medium because denser mediums have a higher angle of refraction.
Answer:

Explanation:
The two cars are under an uniform linear motion. So, the distance traveled by them is given by:

is the same for both cars when the second one catches up with the first. If we take as reference point the initial position of the second car, we have:

We have
. Thus, solving for t:

b. A Boeing 747 airplane
Explanation:
The Boeing 747 airplane will have the most inertia of all. Inertia is the tendency of an object to remain at rest or uniform motion.
- Newton's first law of motion is also regarded as the law of inertia.
- It states that "an object will remain at rest or uniform motion motion unless acted upon by an external force".
- A body that has a large mass will be more resistant to any external force that acts on it.
- The Boeing 747 has the most mass of all and will have the most inertia.
Learn more:
Inertia brainly.com/question/691705
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Answer:

Explanation:
Average velocity is defined as the ratio of total displacement of the motion and total time taken in that motion
here we know that initially the sky diver drops without opening parachute by total displacement 625 m
then she open her parachute and drop another 362 m
so first it took time t = 15 s to drop without open parachute
then it took t = 139 s to drop next displacement
so here total displacement is given as

total time is given as

so average velocity is given as


Answer:
The answer is "
".
Explanation:
Cavity and benzene should be extended in equal quantities.


