Conservation of momentum and % of energy loss

In summary, the question posed is whether a given percent of energy loss in a collision affects the final velocities of the objects involved. It is determined that if there is no energy loss, the final velocities would be faster than if there is a 10% energy loss. However, momentum is still conserved even if energy loss can change the final velocities, as momentum is a vector while energy is a scalar.
  • #1
Ocata
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Suppose a block of 10kg at 10m/s collides into a block of 5kg at 0m/s.

Does a given percent of energy loss in the collision affect the final velocity of the blocks after the collision?

For instance, if there is no energy lost in the collision, would the final velocities be faster than if there is 10% energy loss in the collision? If so, then, how is momentum conserved if energy loss can change the final velocities?

Thank you
 
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  • #2
Ocata said:
if there is no energy lost in the collision, would the final velocities be faster than if there is 10% energy loss in the collision?
Yes.
Ocata said:
then, how is momentum conserved if energy loss can change the final velocities?
Momentum is a vector (direction matters), but energy is a scalar (direction does not matter). Consider two objects with equal masses and speeds, moving in opposite directions. The total energy depends on the speed. The total momentum is zero, regardless of the speed.
 
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Thank you jtbell
 

FAQ: Conservation of momentum and % of energy loss

1. What is conservation of momentum?

Conservation of momentum is a fundamental principle in physics that states that the total momentum of a closed system remains constant over time, regardless of any internal changes within that system. This means that in any interaction or collision between objects, the total momentum before the interaction is equal to the total momentum after the interaction.

2. How is momentum calculated?

Momentum is calculated by multiplying an object's mass by its velocity. The formula for momentum is p = m * v, where p is momentum, m is mass, and v is velocity. Momentum is a vector quantity, meaning it has both magnitude and direction.

3. What is the relationship between conservation of momentum and energy loss?

Conservation of momentum and energy loss are closely related in the context of collisions. In an ideal, perfectly elastic collision, the total momentum and kinetic energy before and after the collision are equal. However, in real-world collisions, some energy is lost to other forms such as heat and sound, resulting in a decrease in the total amount of energy in the system.

4. How is the percentage of energy loss calculated?

The percentage of energy loss in a collision can be calculated by taking the difference between the initial kinetic energy and the final kinetic energy, and then dividing that by the initial kinetic energy. This value is then multiplied by 100 to get the percentage. The formula for calculating the percentage of energy loss is (KEi - KEf)/KEi * 100, where KEi is the initial kinetic energy and KEf is the final kinetic energy.

5. Why is conservation of momentum important in understanding the behavior of objects?

Conservation of momentum is important because it helps us understand and predict the behavior of objects in motion. It allows us to analyze and calculate the outcomes of interactions and collisions between objects, and it is a fundamental principle in many areas of physics, including mechanics, thermodynamics, and electromagnetism.

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