Advanced Physics Through Inquiry 1 Teacher Guide

(PS-2848)

Teacher guide featuring 15 labs designed for Advanced Placement Physics 1.

Conservation of Momentum

Lab Summary

Students use a motion sensor and a dynamics system to demonstrate that linear momentum and kinetic energy are conserved in an elastic collision, and linear momentum is conserved but kinetic energy is not conserved in an inelastic collision.

Theory

How is the total linear momentum and kinetic energy of a two-object system affected by a collision? Experimentally demonstrate that linear momentum and kinetic energy are conserved in an elastic collision, and that linear momentum is conserved but kinetic energy is not conserved in an inelastic collision.

Method

The Structured version of this lab activity is divided into two parts: Part 1 – Elastic Collisions: Students gently push one cart into a stationary second cart, producing a perfectly elastic collision using the magnetic bumpers on the carts. The magnetic bumpers repel each other without the carts ever making contact. Students use a balance and two motion sensors to measure the mass of the carts and the velocity of each cart just before and just after the collision, and then use those values to calculate the total momentum and kinetic energy of the system before and after the collision. Students repeat this process two additional times, increasing the mass of the stationary cart each time. Student data should show that the momentum and kinetic energy of the two car system are the same before and after the elastic collision in each trial. Part 2 – Inelastic Collisions: Students follow the same procedure as in Part 1, but use the Velcro® bumpers on the carts instead of the magnetic bumpers, producing an inelastic collision in which the two carts stick together. The mass of each cart is measured in each trial, along with each cart's velocity just before and just after the collision. Using their measured values for mass and velocity, students calculate the total momentum and kinetic energy of the system before and after the collision in each trial. Student data should show that the total momentum of the system is the same before and after the inelastic collision in each trial, but the kinetic energy is not.

Sensors / Equipment Used:

PASPORT Motion Sensor

(PS-2103A)

The PASPORT Motion Sensor accurately measures position, velocity, and acceleration of a target. Can be used to track the motion of carts, balls, people and more.

PAScar (Set of 2)

(ME-6950)

A feature-rich dynamics cart for virtually friction-free motion on a dynamics track.

PAStrack

(ME-6960)

Connect two 0.5m length tracks and use with PAScars to study motion.

Ohaus Scout SKX Balance 2000g

(SE-8757B)

Combines range, resolution and low cost, making it ideal for the student science lab. 2000 g version.

Materials Used:

The Ohaus Scout Pro Balance 2000g listed in the Materials and Equipment section is for classroom use, not individual lab stations.

The Associated Bundle:

Advanced Physics 1 Starter Bundle

(PS-2815)

Equipment and sensor starter bundle for performing 8 experiments in the Advanced Physics through Inquiry 1 Teacher Guide.

Interface Required

This experiment may require software and an interface for data collection.