Can the kinetic energy of an object be negative? Can the potential energy of an object be negative? Can a potential energy funct
1 answer:
Answer:
Kinetic energy cannot be negative
potential energy is a reference dependent quantity and it can be positive as well as negative both
Since potential energy is defined only for conservative force so it can not be found for friction force
Explanation:
Kinetic energy of an object is given by the formula
here we know that
m = mass of object that can not be negative
v = speed of the object and since its square is given here so it can not be negative
so Kinetic energy is always positive
potential energy is given as the energy due to the virtue of the position of object
so it is
so potential energy is a reference dependent quantity and it can be positive as well as negative both
Since potential energy is defined only for conservative force so it can not be found for friction force
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Answer:
The speed decreases 75%.
Explanation:
- Since no friction present, assuming no external forces acting during the three collisions, total momentum must be conserved.
- For the first collission, only mass 1 is moving before it, so we can write the following equation:
- Since both masses are identical, and they stick together after the collision, we can express the final momentum as follows:
- From (1) and (2) we get:
- v₁ = v₀/2 (3)
- Since the masses are moving on a frictionless 1D track, the speed of the set of mass 1 and 2 combined together before colliding with mass 3 is just v₁, so the initial momentum prior the second collision (p₁) can be expressed as follows:
- Since after the collision the three masses stick together, we can express this final momentum (p₂) as follows:
- From (4) and (5) we get:
- v₂ = v₀/3 (6)
- Since the masses are moving on a frictionless 1D track, the speed of the set of mass 1, 2 and 3 combined together before colliding with mass 4 is just v₂, so the initial momentum prior the third collision (p₂) can be expressed as follows:
- Since after the collision the four masses stick together, we can express this final momentum (p₃) as follows:
- From (7) and (8) we get:
- v₃ = v₀/4
- This means that after the last collision, the speed will have been reduced to a 25% of the initial value, so it will have been reduced in a 75% regarding the initial value of v₀.