Understand Momentum and Impulse in Physics
Learn about momentum and impulse in physics, their definitions, relationships, and practical applications. Explore key concepts through examples, questions, and group work activities. Enhance your understanding of forces and motion in this comprehensive guide.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
You are allowed to download the files provided on this website for personal or commercial use, subject to the condition that they are used lawfully. All files are the property of their respective owners.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.
E N D
Presentation Transcript
Momentum the quantity of motion 7.1
Objectives Define momentum. Define impulse and describe its relationship to momentum.
Whats the point? Nature keeps careful account of momentum.
Think Question Which process requires more time? A. Pulling as hard as you can to accelerate a little red wagon from rest to a speed of 1 m/s. B. Pulling as hard as you can to accelerate a horse trailer from rest to a speed of 1 m/s. C. The two take the same amount of time.
Think Question Which process requires more force? A. Accelerating a little red wagon from rest to a speed of 1 m/s in ten seconds. B. Accelerating a horse trailer from rest to a speed of 1 m/s in ten seconds. C. The two take the same force.
Example Problem Show that when a constant net force F is applied to an object of mass m for a time t, its change in velocity is v = F t m Strategy: We can find acceleration using Newton s second law a = F/m. Then we can find v using the definition a = v/ t.
Group Work 1. From mass m, net force F, and duration t, find acceleration a and velocity change v. t v a m F 1 kg 10 N 1 s 1 kg 10 N 10 s 1 kg 1 N 10 s 10 kg 10 N 10 s
Impulse Impulse J = F t where F Is net force t is duration Impulse is a vector.
Question Two objects of different masses move at the same speed. Which one is harder to stop? A. The lighter object. B. The more massive object.
Question Two objects with the same mass move at different speeds. Which one is harder to stop? A. The faster object. B. The slower object.
Momentum Formula p = mv momentum is a vector.
Question Two spaceships have the same velocity, with one s mass twice the other s. The heavy one s momentum is: A. more than twice the light one s momentum. B. twice the light one s momentum. C. the same as the light one s momentum. D. half the light one s momentum. E. less than half the light one s momentum.
Question Two spaceships have the same mass, but one s speed is twice the other s. The faster one s momentum is: A. more than twice the slower one s momentum. B. twice the slower one s momentum. C. the same as the slower one s momentum. D. half the slower one s momentum. E. less than half the slower one s momentum.
Group Work 2. What are the units of a. impulse? b. momentum?
Group Work 3. From m, F, t, v, find impulse J and momentum change p. t p m F J 1 kg 10 N 1 s 1 kg 10 N 10 s 1 kg 1 N 10 s 10 kg 10 N 10 s
Group Work 4. Show that when a net force F is applied to an object of mass m for a time t, its change in momentum is p = F t Hint: You can find its momentum change from its mass and its velocity change.
Impulse-Momentum Theorem Impulse = F t. F t = ma t = m v = (mv) = p So impulse = change in momentum
Question Which changes its momentum the most? A. A moving object that stops when it hits a barrier. B. A moving object that bounces back from a barrier. Hints: How is p defined? Momentum is a vector. Which receives the greater impulse?
Rebound and Momentum final p initial p initial p final p p final p initial p initial p final p = 0 p
Momentum and Kinetic Energy Momentum depends on velocity momentum is a vector direction matters momentum is changed by impulse ? ? Kinetic energy depends on speed kinetic energy is a scalar direction does not matter kinetic energy is changed by work ? ?
