2015-02-12 Freshman Science Physics Activity 2
Created 3 years ago
We discuss Newton's Second Law and how to interpret in words and symbols (numbers).
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Slide 1 - Coordinated ScienceChapter 1 Activity 2
- Mr. Weisenfeld
Slide 3 - Date: Thu., Feb. 12, 2015
- Objective: Our goal today is to get comfortable using Newton’s 2nd Law (N2L).
- We will know we have learned this when we can use (force = mass times acceleration) correctly with both words and numbers.
Slide 4 - Aaaa
Slide 5 - Entry Task: Choose one of the following statements in your notebook, write it out and complete it based on your experiences in the lab:
- “The greater the constant, unbalanced force pulling on an object, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.”
- “When equal amounts of constant, unbalanced force are used to pull objects having different masses, the more massive object, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.”
Slide 6 - Quiz Question Here
Slide 7 - Make sure you have this definition (the bold words below) in your glossary.
Slide 9 - Let’s look at the definition in pieces.
- “The acceleration of an object”
- Means an object is speeding up
- The units are meters per second per second
- If Speed is meters per second (like miles per hour, or feet per second)
- Then Acceleration is (meters per second) per second
- An object that is getting faster has more (meters per second) every second.
Slide 11 - In the following simulation
- Click on Acceleration to get started
- 2. Check to show speed and acceleration of the box.
- 3. Click on the black arrows to apply a force to the box.
Slide 13 - You should have seen (go back if you have to):
- Unless the force applied is greater than friction, the box won’t move.
- If the force is greater than friction, the box will have an acceleration.
- If the box has an acceleration, then the speed is increasing.
- If you stop pushing, the box will slow down and stop due to friction.
- If you start pushing against the motion, it will slow down quicker.
- If you turn off friction, a small force will get the box moving, faster and faster and faster…
- If you give a small push and then stop, the box will move at a constant velocity when there is no friction.
Slide 14 - Next piece of the definition.
- “The acceleration of an object is directly proportional to the unbalanced force acting on it”
- Means that if you don’t have an unbalanced (or net) force, nothing is going to move.
- Means that the harder you push the greater the acceleration.
- * Go back to the simulation and try it right now if you don’t believe me…
Slide 16 - Next piece of the definition.
- “The acceleration of an object is directly proportional to the unbalanced force acting on it and inversely proportional to the objects mass.”
- Now keep the force constant and change the mass.
- Inversely proportional means that if you double the mass the acceleration goes down by 1/2, for the same force.
- * Go back to the simulation and try pushing on two boxes, instead of just one…
Slide 18 - The last piece of the definition.
- “…The direction of the acceleration is the same as the direction of the unbalanced force.”
- In pictures, this box has a net force (greater force, unbalanced force) to the right, and so it is accelerating to the right.
Slide 20 - That was N2L in words now how about symbols?
- If you are given any two of , , or , you can find the third.
Slide 21 - Let’s do a problem from the book, pg 25, problem #1
Slide 22 - Sprinter
Slide 23 - Long Jumper
Slide 24 - Shot put ball
Slide 25 - Ski jumper
Slide 26 - Hockey player
Slide 27 - Running back
Slide 28 - Thanks for listening!