Answer:
option (B) is the correct option.
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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:
When they are connected in series
The 50 W bulb glow more than the 100 W bulb
Explanation:
From the question we are told that
The power rating of the first bulb is 
The power rating of the second bulb is 
Generally the power rating of the first bulb is mathematically represented as

Where
is the normal household voltage which is constant for both bulbs
So

substituting values

Thus the resistance of the second bulb would be evaluated as

From the above calculation we see that

This power rating of the first bulb can also be represented mathematically as

This power rating of the first bulb can also be represented mathematically as

Now given that they are connected in series which implies that the same current flow through them so

This means that

So when they are connected in series

This means that the 50 W bulb glows more than the 100 \ W bulb
Compared to the charge on a proton, the amount of charge on an electron is same and has the opposite sign