Mechanical energy and momentum conservation

In summary, mechanical energy is the sum of potential energy and kinetic energy in a system, while momentum conservation is the principle that states that the total momentum of a system remains constant in the absence of external forces. According to the law of conservation of energy, mechanical energy is conserved in a closed system and in collisions between two objects, the total momentum before and after the collision remains constant. Real-life examples of mechanical energy and momentum conservation can be seen in various objects and activities, such as a pendulum swinging, a rollercoaster moving, and collisions in sports like billiards or ice hockey.
  • #1
yolo123
63
0
Mechanical energy is conserved whenever momentum is conserved. T/F?

My guess is true:
If momentum is conserved, no external forces are applied on the system. Hence mechanical energy can't change! (No change in PE, no change in KE).

BUT: My answer booklet says FALSE! Why?
 
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  • #2
Momentum is conserved when there's an inelastic collision, but kinetic energy isn't. That's one typical example.
 

FAQ: Mechanical energy and momentum conservation

What is mechanical energy?

Mechanical energy is the sum of potential energy and kinetic energy in a system. Potential energy is the energy stored in an object due to its position or configuration, while kinetic energy is the energy of motion.

How is mechanical energy conserved?

According to the law of conservation of energy, mechanical energy is conserved in a closed system, meaning that it cannot be created or destroyed. It can only be transferred from one form to another.

What is momentum conservation?

Momentum conservation is the principle that states that the total momentum of a system remains constant in the absence of external forces. This means that the total mass and velocity of a system will remain constant unless acted upon by an external force.

How is momentum conserved in collisions?

In collisions between two objects, the total momentum before the collision is equal to the total momentum after the collision, as long as there are no external forces acting on the system. This is known as the law of conservation of momentum.

What are some real-life examples of mechanical energy and momentum conservation?

Some real-life examples of mechanical energy conservation include a pendulum swinging, a rollercoaster moving along a track, and a moving car. Momentum conservation can be seen in sports such as billiards or ice hockey, where the momentum of the balls or players is transferred during collisions.

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