The main activity that is involved in studying of physics is the study of natural laws. The study of physics has to do with many aspects of the universe. Physics majorly looks into the natural laws that operate in the universe and describe how they affect matter in relation to time.
Answer:
a)
& 
b) 
c) 
Explanation:
Given:
mass of the book, 
combined mass of the student and the skateboard, 
initial velocity of the book, 
angle of projection of the book from the horizontal, 
a)
velocity of the student before throwing the book:
Since the student is initially at rest and no net force acts on the student so it remains in rest according to the Newton's first law of motion.

where:
initial velocity of the student
velocity of the student after throwing the book:
Since the student applies a force on the book while throwing it and the student standing on the skate will an elastic collision like situation on throwing the book.

where:
final velcotiy of the student after throwing the book
b)



c)
Since there is no movement of the student in the vertical direction, so the total momentum transfer to the earth will be equal to the momentum of the book in vertical direction.



Answer:
Eletromagnetic radiation which is also known as visible light.
Explanation:
Copper is the best material
Explanation:
Mirrors consist of reflecting surfaces that reflect light.
Reflection is a phenomenon of light wave (but also of other types of waves) in which a ray of light hits a surface, and then it bounces back into the original medium at a certain angle.
The direction of the reflected ray is determined by the law of reflection:
- The incident ray, the reflected ray and the normal to the surface all lie in the same plane
- The angle of reflection is equal to the angle of incidence (where both angles are measured between the ray and the normal to the surface)
A plane mirror is a type of mirror consisting of a straight surface. As a result, light incident perpendicular to the surface is reflected back exactly in the opposite direction.
The image formed by a plane mirror is:
- The same size as the object
- Virtual (it is located behind the mirror)
- Laterally inverted
- Upright