Answer: it’s the third one ☝️
Answer:
A) and B) are correct.
Explanation:
If the object is at rest, it means that no net force is exerted on it.
As the object experiences a downward gravitational force from Earth, in order to be at rest, it must experience an upward force with the same magnitude as the gravitational force on the object.
This force is supplied by the normal force, which can adopt any value in order to meet the condition imposed by Newton´s 2nd Law, and is always perpendicular to the surface on which the object is placed (in this case, the ground).
At a molecular level, this normal force is supplied by the bonded molecules of the ground that behave like small springs being compressed by the molecules of the object, exerting an upward restoring force upward on them.
So, the statements A) and B) are true.
2000J
Explanation:
Given parameters:
Extension = 0.5m
Spring constant = 16000N/m
Unknown:
Energy stored in the bow string = ?
Solution:
The energy stored in a bow string is an elastic potential energy.
It can be calculated using the expression below;
Elastic energy = 
K e²
Where k is the spring constant
e is the extension
Input the parameters;
Elastic energy = K e²
= x 16000 x 0.5²
= 2000J
learn more:
Potential energy brainly.com/question/10770261
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