Introductory Perfectly Inelastic Collision Problem Demonstration

Summary

In this engaging physics lesson, Mr. P. and his students explore a perfectly inelastic collision involving a brass ball and a cart. By applying the principle of conservation of momentum, they calculate the final velocity of the system. The experiment demonstrates how momentum is conserved, but kinetic energy is not. The class also calculates the error between predicted and observed values. The lesson ends on a fun note with the students discussing 'Fruit Day,' where they dress up as various fruits, humorously debating what counts as a fruit.

Takeaways

• 😀 A brass ball is thrown into a cart in a perfectly inelastic collision where the two objects stick together.
• 😀 Momentum is conserved in all types of collisions, including perfectly inelastic collisions.
• 😀 Kinetic energy is not conserved in perfectly inelastic collisions, as energy is lost when the objects stick together.
• 😀 The mass of the cart is 0.599 kg, and the mass of the brass ball is 0.066 kg.
• 😀 The velocity of the brass ball before the collision is calculated to be -1.58125 m/s based on its position change over time.
• 😀 The analysis of the collision is done entirely in the x direction, applying conservation of momentum.
• 😀 Conservation of momentum equation is used to relate the initial and final velocities of the cart-ball system.
• 😀 Since the ball and cart stick together, they have the same final velocity after the collision.
• 😀 The final velocity of the cart and the ball system is predicted to be -0.15694 m/s, or approximately -0.16 m/s.
• 😀 The observed final velocity is -0.156 m/s, resulting in a small error of about 0.60% between predicted and observed values.
• 😀 The script ends with a light-hearted discussion on fruit day, where students and the teacher dress up as different fruits, showcasing the fun atmosphere in the classroom.

Q & A

What type of collision is described in the video?

The collision described in the video is a perfectly inelastic collision, where the two objects stick together after the collision.

Is momentum conserved during a perfectly inelastic collision?

Yes, momentum is conserved in all collisions, including perfectly inelastic ones.

Is kinetic energy conserved in a perfectly inelastic collision?

No, kinetic energy is not conserved in a perfectly inelastic collision. Kinetic energy is only conserved in elastic collisions.

What is the total mass of the cart in the problem?

The total mass of the cart is 0.599 kilograms.

How is the velocity of the brass ball before the collision calculated?

The velocity of the brass ball before the collision is calculated using the change in position over time. It moves from 0.566 meters to 0.313 meters in 0.16 seconds, giving a velocity of -1.58125 meters per second.

What does the conservation of momentum equation represent in this case?

The conservation of momentum equation in this case states that the initial momentum of the ball plus the initial momentum of the cart is equal to the final momentum of the ball and the cart combined, since they move together after the collision.

Why is the initial velocity of the cart considered zero?

The initial velocity of the cart is zero because it is stationary before the collision.

What is the predicted final velocity of the cart and ball system after the collision?

The predicted final velocity of the cart and ball system is -0.15694 meters per second, which rounds to -0.16 meters per second when expressed with two significant digits.

How is the relative error in the predicted final velocity calculated?

The relative error is calculated by subtracting the predicted final velocity from the observed final velocity, dividing the result by the predicted value, and multiplying by 100. The error is -0.60%.

What is the final observed velocity of the cart after the collision?

The observed final velocity of the cart is -0.156 meters per second.