NECT Gr 12 Conservation of Linear Momentum

Summary

This video demonstrates the principle of conservation of linear momentum through experiments involving Newton's Cradle and explosive trolleys. It explains how momentum is conserved in an isolated system during collisions and explosions, emphasizing the importance of leveling the track and ensuring no external forces act on the system. The experiment showcases how trolleys of varying masses hit their stoppers simultaneously, applying the principle of conservation of momentum. The conclusion verifies that momentum is indeed conserved in inelastic explosions, providing hands-on proof of this fundamental physical principle.

Takeaways

• 😀 The principle of conservation of linear momentum states that the total momentum of an isolated system remains constant.
• 😀 Newton's Cradle demonstrates the principle of conservation of momentum by showing how momentum is transferred between balls in a chain reaction.
• 😀 When one ball is lifted and released, it strikes the next ball in line, transferring its momentum until the last ball swings up.
• 😀 The total momentum before and after the collision in Newton's Cradle is conserved, illustrating the conservation of momentum.
• 😀 In the investigation with trolleys, an explosion (inelastic collision) is used to test whether momentum is conserved in isolated systems during explosions.
• 😀 The system is isolated by ensuring the track is perfectly level so that no external forces affect the motion of the trolleys.
• 😀 The track's leveling process is essential to ensure the system is isolated, allowing the experiment to accurately test the principle of momentum conservation.
• 😀 When two trolleys of equal mass are released, they accelerate at the same rate, and their final velocities are the same, allowing them to hit the stoppers simultaneously.
• 😀 In experiments with unequal trolley masses, the principle of conservation of momentum is used to calculate the starting positions of the trolleys so that they hit their stoppers at the same time.
• 😀 When one trolley has twice the mass of the other, the distances they must travel are calculated to ensure they reach their stoppers simultaneously based on the conservation of momentum.
• 😀 For trolleys with three times the mass difference, the track is divided into sections so that the red trolley (heavier) travels a shorter distance than the blue trolley (lighter) to ensure simultaneous stopping.
• 😀 The successful synchronization of the trolleys hitting their stoppers at the same time confirms that the principle of conservation of momentum holds true in these experiments.

Q & A

What does the principle of conservation of linear momentum state?

The principle of conservation of linear momentum states that the total linear momentum of an isolated system remains constant, meaning that the total momentum before an event is equal to the total momentum after the event.

How is the principle of conservation of momentum demonstrated using Newton's Cradle?

In Newton's Cradle, when one ball is lifted and released, it strikes the next ball, transferring momentum through the series of balls until the last ball swings out. This demonstrates the transfer and conservation of momentum in an isolated system.

Why is the system in Newton's Cradle considered isolated?

Newton's Cradle is considered an isolated system because no external forces, such as friction or air resistance, significantly affect the motion of the balls, allowing momentum to be transferred from one ball to another without loss.

What happens when two balls collide in the Newton's Cradle?

When one ball collides with the others in the Newton's Cradle, momentum is transferred through the balls, and the last ball swings out with the same velocity but in the opposite direction.

Why is momentum conserved during a collision in Newton's Cradle?

Momentum is conserved during a collision in Newton's Cradle because it operates in an isolated system where no external forces act on the balls, ensuring that the total momentum before and after the collision remains the same.

How does the experiment with trolleys differ from the Newton's Cradle experiment?

The trolley experiment investigates the conservation of momentum during explosions (which are inelastic), where the trolleys are released and move in opposite directions after being triggered. Unlike Newton's Cradle, which deals with collisions, this focuses on inelastic events where kinetic energy is not conserved, but momentum still is.

Why is it important to ensure the track is perfectly level in the trolley explosion experiment?

It is crucial to ensure the track is perfectly level because any slope would create an external force due to gravity, which would influence the motion of the trolleys and prevent the system from being truly isolated, compromising the experiment.

What role does the spirit level play in the trolley explosion experiment?

The spirit level is used to ensure that the track is horizontal. It helps to check the alignment of the track to make sure that no external forces, like gravity, affect the movement of the trolleys during the experiment.

How do the masses of the trolleys affect the experiment's results?

The masses of the trolleys affect the distances they travel in order to hit their stoppers at the same time. By using the principle of conservation of momentum, the starting positions of the trolleys are adjusted based on their masses, with the lighter trolley traveling a longer distance to balance the momentum.

What happens when one trolley has three times the mass of the other in the experiment?

When one trolley has three times the mass of the other, the lighter trolley travels a longer distance to ensure that both trolleys hit their stoppers at the same time. The track is divided into parts, with the heavier trolley traveling a smaller portion and the lighter trolley covering a larger portion of the track.