Earth & Space Science
You will explore Newtons third law using the example of the working principles of rockets.
After completing this tutorial, you will be able to complete the following:
Sir Isaac Newton was born in England, and investigated many areas, including mathematics, physics, and astronomy. He is probably best known for his three laws of motion.
Newton's first law states, "An object in motion will continue its motion unless acted upon by an unbalanced force. An object at rest will remain at rest unless acted upon by an unbalanced force." Newton's second law goes on to state that an object's acceleration depends on the net force acting on it and the mass of the object. This law is generally represented with the mathematical relationship: F = ma. Newton's third law states, "For every action, there is an equal and opposite reaction."
Understanding how rockets work requires an understanding of all of three of Newton's laws of motion, but especially the first and third laws. A rocket will continue its state of motion or stay at rest when gas is not being expelled. However, when the rocket pushes gas backwardbackwards with some force, the gas will push the rocket and the astronaut forward with the same amount of force. This allows the astronaut to accelerate, or change his velocity.
As soon as the rocket is turned off so that gas is no longer being forced out, the astronaut will continue moving with that speed until another force acts upon him. Since there is no friction in space, there is no reason for the astronaut to change his speed unless he is engaging the rockets. In order to stop the motion of the astronaut, gas must be expelled so that the gas is pushing on the rocket in a direction opposite to its motion.
|Approximate Time||20 Minutes|
|Pre-requisite Concepts||Learners should be familiar with forces and Newton's first law.|
|Course||Earth & Space Science|
|Type of Tutorial||Concept Development|
|Key Vocabulary||action, reaction, Newtons third law|