B is the answer because it causes impact and collides together.
Answer:
k = 3.5 N/m
Explanation:
It is given that the time period the bob in pendulum is the same as its time period in spring mass system:


where,
k = spring constant = ?
g = acceleration due to gravity = 9.81 m/s²
m = mass of bob = 125 g = 0.125 kg
l = length of pendulum = 35 cm = 0.35 m
Therefore,

<u>k = 3.5 N/m</u>
The answer would be 'First rocks formed on Earth'.
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