Explanation:
- Newton's first law of motion:
"An object at rest (or in uniform motion) remains at rest (or in uniform motion) unless acted upon an unbalanced force
In this situation, we can apply Newton's first law to the keys of the keyboard that are not hit by the fingers of the man. In fact, as no force act on the keys, they remain at rest.
- Newton's second law of motion:
"The acceleration experienced by an object is proportional to the net force exerted on the object; mathematically:

where F is the net force, m is the mass of the object, and a its acceleration"
In this case, we can apply Newton's second law to the keys of the keyboard that are hit by the man: in fact, as they are hit, they experience a downward force, and therefore they experience a downward acceleration.
"Newton's third law of motion:
"When an object A exerts a force on an object B (action force), then object B exerts an equal and opposite force on object A (reaction force)"
Here We can apply Newton's third law to the pair of objects finger-key: in fact, as the finger apply a force on the key (action force), then the key exerts a force back on the finger (reaction force), equal and opposite.
Answer:
The inventor of the electric cell was:
Alessandro Volta (in other words, Volta)
Explanation:
Fission and fusion are two processes that release very little amounts of energy.
Answer:
has free electrons
Explanation:
A conductor has free electrons while an insulator does not. Free electrons are electrons which are not bounded tightly to their parent atoms, and are free to move given the right conditions (ie. a strong EM field).
<span>The question is asking us to fill in the gap in: (gap) is a force of attraction that occurs between objects due to their mass.The correct answer is b. gravity. People don't know that gravity works both ways: both objects atract each. The reason why we're more attracted to Earth than Earth is pulled to us is that Earth has a much higher mass - the bigger the mass, the stronger the atraction</span>