Lab Report

Objective:
Students will explore the concepts of momentum, kinetic energy, and the differences between elastic and inelastic collisions using PhET’s Collision Lab simulation.

Part 1: Setting Up the Experiment

1. Accessing the PhET Simulation:

   • Go to the PhET website and launch the Collision Lab simulation.

   • Select the Exploration in Two Dimensions option.

2. Understanding the Interface:

   • Take a few minutes to explore the features of the simulation:

     • Adjusting mass, velocity, and initial position of two objects.

     • Recording observations using the data display panel.

   • Look at the graphs provided in the simulation for momentum, velocity, and energy.

Part 2: Performing the Elastic Collision Experiment

1. Set the parameters:

   • Set the mass of Ball 1 to 0.5 kg and Ball 2 to 1.5 kg.

   • Set the initial velocity of Ball 1 as Vx=0.5 m/s, Vy=0.5 m/s.

   • Set the initial velocity of Ball 2 to 0 m/s (stationary).

   • Place Ball 1 at X=0,Y=0 and Ball 2 at X=0.5,Y=0.5.

2. Run the experiment:

   • Record the velocities of both balls before and after the collision.

   • Observe and note whether kinetic energy is conserved (look at the energy graphs in the simulation).

   • Take a screenshot of the graph showing the velocity and energy changes.

Part 3: Performing the Inelastic Collision Experiment

1. Set the parameters:

   • Set the masses and position of the two balls the same as in Part 2.

   • Set the velocity of Ball 1 as Vx=0.5 m/s, Vy=0.5 m/s.

   • Ball 2 remains stationary with Vx=0 m/s,Vy=0 m/s.

2. Enable inelastic collision mode in the settings (if available).

3. Run the experiment:

   • Observe how the two objects stick together after the collision.

   • Record the final velocity of the combined object.

   • Compare the momentum before and after the collision using the simulation graphs.

   • Note whether kinetic energy is conserved.

Part 4: Data Analysis

1. Analyze the data using the position vs. time graphs. Track the velocities before and after the collisions using ImageJ (if required).

2. Calculate the momentum before and after the collision for both the elastic and inelastic cases using the data from the simulation: p=mxV

1. Describe the differences between elastic and inelastic collisions based on your simulation results. What happens to kinetic energy in each type of collision?

2. Momentum Conservation:

   • Calculate the total momentum before and after the collision for both elastic and inelastic collisions.

   • Does the total momentum stay constant? Explain why momentum is conserved.

3. Kinetic Energy Conservation (Elastic Collision):

   • Is kinetic energy conserved in the elastic collision?

   • Calculate the total kinetic energy before and after the elastic collision. Compare the values and explain your findings.

4. Kinetic Energy Loss (Inelastic Collision):

   • Calculate the total kinetic energy before and after the inelastic collision.

   • By how much did the kinetic energy decrease? Explain where the lost energy went.

5. Graphs:

   • Create a graph of momentum vs. time for both collisions.

   • Create a graph of kinetic energy vs. time for both collisions.

Problem 1: Elastic Collision in One Dimension

• Setup: Two balls collide elastically. Ball 1 (mass = 0.4 kg) moves at 2 m/s, and Ball 2 (mass = 0.8 kg) is stationary.

• Question:

  1. Calculate the velocities of both balls after the collision.

  2. Confirm that both momentum and kinetic energy are conserved.

Problem 2: Inelastic Collision in One Dimension

• Setup: Two balls collide inelastically. Ball 1 (mass = 0.5 kg) moves at 3 m/s, and Ball 2 (mass = 1.5 kg) is stationary. After the collision, the two balls stick together.

• Question:

  1. Calculate the velocity of the combined mass after the collision.

  2. Calculate the kinetic energy before and after the collision and determine the percentage of energy lost.

Problem 3: Two-Dimensional Collision

• Setup: Ball 1 (mass = 0.6 kg, velocity = 2 m/s at an angle of 30 degrees to the x-axis) collides with Ball 2 (mass = 1.2 kg, stationary).

• Question:

  1. Calculate the momentum of both balls before the collision in the x- and y-directions.

  2. If the collision is perfectly inelastic, what is the final velocity and direction of the combined mass?

Problem 4: Energy Dissipation in Inelastic Collisions

• Question:
  Why is energy not conserved in inelastic collisions? Give real-world examples of where energy goes during inelastic collisions (e.g., car crashes, football tackles).

1. Worksheet (40%): Completeness and accuracy of theory, calculations, and explanations.

2. Assignment (30%): Detailed report, correct use of formulas, analysis, and discussion of results.

3. Problem Set (30%): Correctness of solutions, step-by-step calculations, and proper explanation.

Each lab group should download the Lab Report Template and fill in the relevant information as you experiment. Each group member should answer the Worksheet, Assignment, and Problem individually. Since each lab group will turn in an electronic copy of the lab report, rename the lab report template file. The naming convention is:

[Short Experiment Number]-[Student ID].PDF

Submit the Lab Report in PDf format