The absence of external forces will make the pucks move in the form of a uniform circular motion.
<h3>What is a circular motion?</h3>
It should be noted that a circular motion simply means the movement of an object along the circumference of the circle.
In this case, the absence of external forces will make the pucks move in the form of a uniform circular motion.
If the friction is absent, the pucks will continue to move on the same path due to the first law of Newton and the law of conversation of energy. In this case,the results will match the predictions until there's loss in energy.
Learn more about circular motion on:
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Answer:The correct options are:
1. A system is a group of objects analyzed as one unit.
2. Energy that moves across system boundaries is conserved.
Explanation:
A system is defined as group of interrelated or interacting items existing as a single unit or a whole to achieve a specific objective.Energy lost by the system is equal to the energy gained by the surroundings.
Two statements are true about a system:
- A system is a group of objects analyzed as one unit.
- Energy that moves across system boundaries is conserved.
Answer:

Explanation:
consider the mass of each train car be m
m₁ = m₂ = m₃ = m
speed of the three identical train
u₁ = u₂ = u₃ = 1.8 m/s
m₄ = m u₄ = 4.5 m/s
m₅ = m u₅ = 0 (initial velocity )
final velocity
v₁ = v₂ = v₃ = v₄ = v₅ = v
using conservation of momentum
m₁u₁ + m₂u₂ + m₃u₃ + m₄u₄ + m₅u₅ = m₁v₁ + m₂v₂ + m₃v₃ + m₄v₄ + m₅v₅
m (1.8 + 1.8 + 1.8 +4.5) = 5 m v


The answer to this is aluminum foil.