Answer:
B. 6 cm
Explanation:
First, we calculate the spring constant of a single spring:

where,
k = spring constant of single spring = ?
F = Force Applied = 10 N
Δx = extension = 4 cm = 0.04 m
Therefore,

Now, the equivalent resistance of two springs connected in parallel, as shown in the diagram, will be:

For a load of 30 N, applying Hooke's Law:

Hence, the correct option is:
<u>B. 6 cm</u>
Answer:
The negative electrode of a battery has an excess of positive charge
Explanation:
This is because in every battery, there is a negative electrode ( cathode ) and only positive charge is deposited on it.
For other statements:
Batteries donot store electric charge but they store chemical energy
Some batteries donot use metals for the flow of electrons, but some use hydrogen gas at a pressure of 1 atmosphere.
Answer:
No the gravity of the moon pulls the water making high tide
Explanation:
Answer:
-6112.26 J
Explanation:
The initial kinetic energy,
is given by
} where m is the mass of a body and
is the initial velocity
The final kinetic energy,
is given by
where
is the final velocity
Change in kinetic energy,
is given by

Since the skater finally comes to rest, the final velocity is zero. Substituting 0 for
and 12.6 m/s for
and 77 Kg for m we obtain

From work energy theorem, work done by a force is equal to the change in kinetic energy hence for this case work done equals <u>-6112.26 J</u>