The unit of length mist suitable for measuring the thickness of a cell phone is a_________?
1 answer:
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Answer:
the final kinetic energy is 0.9eV
Explanation:
To find the kinetic energy of the electron just after the collision with hydrogen atoms you take into account that the energy of the electron in the hydrogen atoms are given by the expression:
you can assume that the shot electron excites the electron of the hydrogen atom to the first excited state, that is
-10.2eV is the energy that the shot electron losses in the excitation of the electron of the hydrogen atom. Hence, the final kinetic energy of the shot electron after it has given -10.2eV of its energy is:
The book falling to the floor is described by Newton's second law and Newton's third law
Explanation:
Newton's first law of motion states that:
"An object moving at constant velocity (or at rest) keeps moving at constant velocity (or will stay at rest) unless acted upon unbalanced, external forces"
For a book falling to the floor, there is an unbalanced force acting on it (the force of gravity): therefore, we cannot apply Newton's first law.
Newton's second law of motion states that:
"The net force acting on an object is equal to the product between the object's mass, m, and its acceleration, a"
Mathematically:
For the book falling to the floor, F is the force of gravity; therefore, we can apply Newton's second law, and in this case it tells us that the book has a non-zero acceleration during its fall.
In particular, the force of gravity is (where
is the acceleration due to gravity), so the acceleration of the book is
Newton's third law of motion states that:
"When an object A exerts a force (action force) on an object B, then object B exerts an equal and opposite force (reaction force) on object A".
In this case, the Earth is exerting a force (the force of gravity) on the book during its fall: therefore, the book is also exerting a equal and opposite force (reaction force) on the Earth.
Learn more about Newton laws of motion:
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