B. Amplitude
It is the maximum distance from the equilibrium point of the pendulum.
As per the question the mass of the boy is 50 kg.
The boy sits on a chair.
We are asked to calculate the force exerted by the boy on the chair at sea level.
The force exerted by boy on the chair while sitting on it is nothing else except the force of gravity of earth i.e the weight of the body .The direction of that force is vertically downward.
At sea level the acceleration due to gravity g = 9.8 m/s^2
Hence the weight of the boy 
[m is the mass of the body]
we have m = 50 kg.
Hence w = 50 kg ×9.8 m/s^2
=490 N kg m/s^2
= 490 N
Here newton [N] is the unit of force.
Answer:B
Explanation:
For work to be done, the object must move some distance as a result of a force
Based on this information, a psychologist would most likely conclude that Jonah's stress led him toward positive personal changes.
<h3>What is stress?</h3>
When a person is afraid or tensed about something, he overthinks about him and become stressed.
Anxious to the point that he couldn't eat very well without his stomach feeling queasy. As a result of his stress, Jonah increased his time of practicing basketball and asked an old team member to help him develop new skills he needed in order to make the team. After hearing that he made the basketball team a day after tryouts, Jonah went out for a large pizza with the rest of the team players.
As, he is feeling good, he wants to celebrate himself. So, he went to eat pizza with his team players. This shows that he is not stressed but happy.
Thus, ,this information depicts that Jonah's stress led him toward positive personal changes.
Learn more about stress.
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Answer:
what do you mean ???????????
