Friction Lab

Big questions: What is friction? How does it relate to the atomic description of the universe? 

How does static friction differ from kinetic friction? 

How we went about investigating the big question: For this lab, we used a shoe to demonstrate the force of friction. We took the mass of the shoe using a force probe. We then placed the shoe on the table and hooked the force probe onto it. We added brass masses to the shoe, and we slid the shoe across the table. We then recorded the force of static and kinetic friction. The maximum force of the peak on the force probe was the static friction, and the mean of the straight line on our force probe was the kinetic friction. We then analyzed our data by graphing the weight of the shoe vs. the static fiction and the weight of the shoe vs. the kinetic friction. We created equations from the forces of kinetic and static friction. 

Answer to the big question: 

Static friction is present when both objects are stationary. It must be overcome to start an object's motion. Kinetic friction is present when one or more of the objects are in motion. Must be overcome to keep an object moving at constant velocity. In the force of friction, the electrons are on the surface and the force must overcome them. The friction increases for rougher surfaces. In this case, friction depended on the shoe's surface and the surface of the table. The coefficient of static friction is always greater than the coefficient of kinetic friction. Slope was the coefficient of friction, which we represented with "Mu."

The equations were: Ffs= "Mu"s Fn

                                Ffk= "Mu"k Fn 

    

Evidence to support conclusions: Slope was the coefficient of friction for our lab. Our data supports the fact that coefficient of static friction is always greater than the coefficient of kinetic friction. Our slope for static friction was .702, while our slope for kinetic friction was .647. 

How I can used what I learned in a new situation: I can use the equations we found for the force of kinetic friction and the force of static friction in other situations. I can use it to find how much force it takes to get an object moving and to keep it moving. I can also use it to find the coefficient of friction, using normal force. 

How this relates outside of class: A real life example would be a hockey player hitting the puck across the ice. The ice has less friction than asphalt would, but it still has so,e friction. at a certain point the puck will come to a stop due to this friction.          

Collision Lab

Big question:

What is a better conserved quantity in a collision- momentum or kinetic energy?

How we went about investigating the big question:

For our lab, we placed two range finders on a track and used two cars. We then conducted two different collisions. For the elastic collision, Weser the carts up with their spring launchers facing each other, and we then pushed the red car to collide into the blue. We recorded the speed of the carts before and after the collision. For the inelastic collision, we set the carts up with their Velcro sides facing so that they would stick together. We again pushed the red cart towards the blue and recorded the speeds of the carts before and after. 

Answer to the big question:

The answer to the big question was that momentum is the better conserved quantity in a collision. 

Evidence to support answer: 

We used  % difference = [(TOTAL ENERGY_AFTER - TOTAL ENERGY_BEFORE)/(TOTAL ENERGY BEFORE)] x 100% to find the amount of energy that left the system. We then used  % difference = [(TOTAL MOMENTUM_AFTER - TOTAL MOMENTUM_BEFORE)/(TOTAL MOMENTUM BEFORE )] x 100 to find how much momentum left the system. We got the following results: 

 For the elastic collision 7.86% difference of momentum lost was less than the percentage lost for the kinetic energy. In the inelastic collision, the 22% of momentum lost was less than the percentage lost for the kinetic energy as well, so in both collisions momentum was better conserved. 

How I can use what I learned in a new situation: 

I can use the equations for percent difference to figure out how much energy or kinetic energy is lost. I can also use the conservation of momentum theory to plug in and find other values such as velocity.

How this relates outside of class:

This relates to the Large Hadron Collider, which is a particle accelerator. Two high energy particle beams are guided around the tube by electromagnets. The magnets are used to squeeze particles together and increase the chances of collision. This relates to the amount of energy and momentum that is needed in order for the particles to collide.