Featured in PASCO’s Physics through Inquiry Teacher Guide

Physics through Inquiry Teacher Guide


Features over 30 inquiry based labs covering the core topic areas of mechanics, electricity and magnetism, optics, thermodynamics and more.

Newton's Third Law

Lab Summary

Use two force sensors to observe the relationship between an action force and the resulting reaction force.


This experiment clearly illustrates the relationship between an action force and the resulting reaction force. The activity illustrates that:

  • Forces occur in pairs, commonly referred to as "action" and "reaction".
  • Action and reaction forces never act on the same body.
  • Action and reaction forces are always equal in magnitude and opposite in direction.


Determine the force that two dynamics carts exert on each other when they collide on a track. As students explore this interaction, they will vary the mass of the carts as well as which of the carts is moving before the collision occurs.
Determine the force exerted on a friction block as well as the reaction force as the force on a stationary block is gradually increased until it moves with constant velocity.

Sensors / Equipment Used:

PASPORT Force Sensor


Designed to measure both pulling and pushing forces. Uses range from collisions to tug-of-war.

Materials Used:


Dynamics carts ~ 2

Dynamics track

Compact cart mass 250 g

Discover friction accessory

Spring force sensor bumper

Collision cup force sensor bumper

Rubber band

The Associated Bundle:

Physics Standard Sensor Bundle


Contains the probeware needed to perform all 37 lab activities in the Physics through Inquiry lab manual.

Interface Required

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