Conceptual question 9.05

a baseball is thrown vertically upward and feels no air resistance. as it is

a: both its momentum and its mechanical energy are conserved.

b: its kinetic energy is conserved, but its momentum is not conserved.

c: its gravitational potential energy is not conserved, buts its momentum is conserved.

d: its momentum is not conserved, but its mechanical energy is conserved.

e: both its momentum and its kinetic energy are conserved.

Answering the question, a baseball is thrown vertically upward and feels no air resistance. As it is rising, its momentum is not conserved, but its mechanical energy is conserved. This implies the correct answer is D

Since there are no external forces that acted on the baseball, then its total mechanical energy is conserved and its momentum is not conserved. The momentum of the baseball is also not conserved for the same reason, that is, there are no external forces that acted on it.

Mechanical energy is the energy that an object acquired due to its movement or due to its position. This also implies that an object has acquired mechanical energy when it possesses the ability to do work due to its movement or position.  

Mechanical energy can be of two forms, which are kinetic or potential energy. Kinetic energy is the energy an object acquired due to its movement and potential energy is the energy that is stored due to the position of the object.

Conservation of momentum and the newton’s third of law of motion has the same explanations. Conservation of momentum always applies to the collision between objects. When two bodies collide with each other, the forces of the two bodies will be equal and opposite at the same time

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which piece of furniture will have the most inertia and give the furniture movers the most difficulty in moving?  

answer

a 75kg dining table