- Information
- AI Chat
Ph ET 2D Collision Lab
Physics I (Calculus-Based) (PHY 201)
Rowan College of South Jersey
Recommended for you
Preview text
Names: ____________________________, _________________________________
Computer Simulation: Collisions in Two Dimensions
In this experiment you will be using the PHET simulation Collision Lab to explore the relationships between the momentum, impulse, and kinetic energies during two-dimensional collisions.
Objectives : - add momentum vectors – by components and by vector addition - apply the Law of Conservation of Momentum - determine the impulse on an object involved in a collision - determine the role of elasticity on the outcome of collisions
Description The simulation allows you to change the velocity and mass of up to five balls that will collide in two dimensional collisions. When you open the simulation make the following setting changes: - activate velocity and momentum vectors - activate the momenta diagram - deactivate the reflecting border
PreRequisite Skills: Momentum and Impulse
Newton’s first law can also be phrased in terms of momentum: for any closed system of objects, the total momentum remains ____________________. Note that momentum can be exchanged between objects within a closed system. However, the magnitude of the change in momentum for one object must be _________________ to the magnitude of the change in momentum of the other object.
A change in momentum for an object is also referred to as an _____________________________.
Fill in the appropriate units for each quantity: momentum: ___________ impulse: ____________
Settings: Use the Advanced tab. Select 2 Dimensions, Velocity Vectors, Center of Mass, Reflecting Border,
Momenta Diagram and Kinetic Energy. Select MORE DATA. Check “tip to tail” on Momenta.
Exploration:
1. Begin with two balls of equal mass with the second ball at rest. Set the first ball to collide obliquely. Run several trials varying the velocity and amount of obliqueness. What can you say about the relationship between the directions of the two balls after the collision? Demonstrate your observation by copying a sample Momenta Diagram. Determine what four conditions are necessary for this to occur?
2. Now change to masses of 2kg and 3 kg and uncheck “tip to tail”. Change the velocity of each ball (by dragging on the velocity vector or by selecting appropriate velocity components and initial positions) until the total momentum is close to zero as indicated on the Momenta Diagram. Move the three arrows so they are all visible. Adjust the scale on the Momenta Diagram until your arrows just fit inside the grid, then copy the vector diagram in the space to the right. 3. Set the Elasticity to 0, then run the simulation. Describe what happens to the motions of the balls after the collision. How does this relate to the motion of the center of mass? What happened to the Momenta Diagram?
Rewind and run the simulation again. Record the total initial and final kinetic energies of the system in the spaces below.
4. Rewind, set the Elasticity to 50%, and run the simulation again. Record the total initial and final kinetic energies of the system in the spaces below.
Rewind, set the Elasticity to 100%, and run the simulation again. Record the total initial and final kinetic energies of the system in the spaces below.
Describe the effect the elasticity had on the motions of the balls after the collision.
4. Draw the resulting Momenta Diagram at the right.
5. Transfer the data into the table below then calculate the total momentum and direction of each ball.
EK = After the Collision J 2 kg Ball 3 kg Ball v x (m/s) v y (m/s) v x (m/s) v y (m/s) Component Velocities p x (kgm/s) p y (kgm/s) p x (kgm/s) p y (kgm/s) Component Momenta
Total Momentum
calculation: calculation:
Direction (°)
calculation: calculation:
3. Verify the Elasticity of the Collision:
Using the Data given by the simulation for the EKi and EKf you recorded using Show Kinetic Energy.
(__________ )
_________ %
(__________ )
f i
k J k J
E
Elasticity
E
Using the Show Values option, record the magnitude of the speeds and masses below and calculate the elasticity directly.
How do these calculated elasticities compare to the elasticity set in the simulation? ._______________
4. Apply the Law of Conservation of Momentum to analyze the collision in two ways: 1) by components, and 2) using a vector diagram.
Component Method Demonstrate by finding the total px and the total py before and after.
Was momentum conserved in each component directions? ___________________________________
Vector Addition: (Use the data from the component method above.)
Total Initial Momentum Total Final Momentum Calculation – magnitude and direction Calculation – magnitude and direction
Was total momentum conserved within the limits of accuracy in the simulation? ________________
5. Calculate the magnitude and direction of the impulse on the 2 kg ball.
(Breadcrumbs: Record the data for the initial and final momentum vectors for the 2 kg ball. Determine the opposite of the initial momentum. Add the opposite of the initial momentum to the final momentum both graphically and analytically.)
vector diagram calculation (magnitude direction)
6. Calculate the magnitude and direction of the impulse on the 3 kg ball. (Hint: your result should be equal and opposite to your answer to 5.
Ph ET 2D Collision Lab
Course: Physics I (Calculus-Based) (PHY 201)
University: Rowan College of South Jersey
