Newtons Three Laws of Motion

Law #1: If an object is at rest or in motion at a constant speed, it will stay that way unless it experiences a net force.

Law#2: Force equals mass times acceleration, F=ma. Mass and acceleration are indirectly proportional.

Law#3: When two objects interact they exert equal but opposite forces on one another. They feel a force that is...

• The same type(typically normal, friction, or gravitational)
• The same amount(no matter how big or small, the force felt is the same)
• Opposite

Hover Disk Lab

Big Question-What gives rise to a change in motion?

The purpose of this lab was to learn which forces are pulling on certain objects, in this case two people, the ground and a hover disk, by knowing Newtons 1st and 3rd laws. We experimented with a hover disk and learned that it blows air out from the bottom to eliminate friction, allowing it to glide on smooth surfaces. Theoretically if you pushed the disk, and if the surface was infinitely smooth(and if there is no air resistance), it would glide in a straight line forever. For a while we played around with the disk and passed it along to one another, simulating the diagrams in our worksheet. We used interaction diagrams and free body diagrams to chart the forces acting on each individual object. 

In this diagram the disk is on but at rest and has not been pushed yet. The earth has a normal and gravitational force with each object, yet none of the objects are interacting with each other at this time. Its strange to think that the earth and person 1 are feeling the same force from each other but it is true!

We also drew a free body diagram as a second way to show the force between each object

involved.The arrows are vectors that represent the forces acting on the disk. 

This is another diagram we drew, but this time the hover disk is on and being caught by person 2. This is different from the first diagram because the disk and person 2 are now interacting. They have a normal force acting upon them.

Fan Cart Lab

Big Question- What is the relationship between force, mass, and acceleration?

From this lab we learned that F=ma. This means that if the mass increases then the acceleration decreases(and vice versa), to equal the force. In other words, the net force on an object is equal to the mass of the object multiplied by its acceleration. This is proven by the data we collected. Although trial 4 does not fit the pattern, we concluded that this was due to human error. 

As you can see trial 4 is the outlier, so we calculated the percent error to find out our mistakes. 

Real World Connection

I found this video about Newton's Laws of Motion applied to everyday life. I liked how it had multiple examples to show just how common these theories are in the real world, not just in the classroom. In the video it showed a game of pool. The ball would remain still and at rest unless an outside force pushes it.  Once hit, the balls move in the direction that they are expected to depending on the angles that they are hit at. It was interesting for me to see that something as simple as pool can relate to physics.

http://videos.howstuffworks.com/discovery/29421-assignment-discovery-newtons-laws-of-motion-video.htm

Impulse Lab

Big Question: What is the relationship between impulse, force, and time during a collision?

In this lab we learned about impulse, which is a change in momentum for objects in a collision. It is important to know that J stands for impulse(not jules) and that objects in a collision experience equal and opposite impulse because momentum is conserved.The formula for impulse is J= Pafter-Pbefore. 

The computer that we used to calculate velocity gave us a force time graph. From this data we were able to understand that the relationship between impulse, force, and time is J=F x t. The relationship is inversely proportional so if the force goes up the time will go down and ect. but the J value remains the same. 

Real world connection: Airbags are a good connection to what we are learning in class. It slows down the time it takes to make an impact, so the more time it takes the less force you will feel ( because force and time are inversely proportional). 

Collisions Lab

Purpose: The purpose of this lab was to learn about two different types of collisions: elastic and inelastic. In an elastic collision two objects will collide and bounce off of each other. They will have equal but opposite force. In an inelastic collision two objects will collide and then stick together instead of going different directions.  

Equation for momentum: p=mv

Big Question: Which is better conserved, momentum or energy?

We can conclude that total momentum is better conserved by looking at our data. The numbers are closer together than the stats for kinetic energy. This is because kinetic energy can be transferred into heat and sound, but momentum remains the same. 

Real World Connection: A car crash is an example of an inelastic collision. When the cars connect both feel the same amount of force but the car with the greater mass will push the smaller car farther away.