Monday, February 1, 2010

Dyanmics Application: How is Newton's third law responsible for recoil?

this is a Glog I created to show how recoil is attributed to Newton's third law of Motion. The glog explains why there is recoil and it also talks about why bigger and more powerful guns have more recoil.

edited Dynamics application Glog

Friday, January 8, 2010

N2L and friction reflection

In this unit I learned about Newton's second law of motion and about the force of friction. Newton's second law states the for a particular force, the acceleration of the object is proportional to the net force and inversely proportional to the mass of the object. The direction of the force is the same as that of the acceleration. In equation form this is simply: F=m(a). I learned how to apply the knowledge of the second law to determine mass and value of forces when an object is accelerating. When calculation the sum of the forces for an object that is accelerating just set the sum equal to ma instead of zero. I also learned about apparent weight and discovered that the apparent weight of a body is the force the body exerts on whatever it is resting on. Another thing I learned about is pulley systems and add wood machines. This is where there are two connected objects hung over a pulley, with one possibly resting on a table. I was able to create net force equations for these systems and then find the value of different variable. The final thing I learned about was the force of friction, I learned how to calculate friction and the coefficient of friction (expressed in mu). To solve for variables in these types of problems we used equations from both kinematics and dynamics.

What I have found difficult about what we have studied is the problems containing the coefficient of friction. In these problems you use equations from this unit and the last. Sometimes the answer is not apparent at first but when you keep substituting you are able to cancel out variables. I feel that as I get more practices with these types of problems I will be more comfortable solving them.

My problems solving skills are good in my opinion, and I feel that they have improved over this last unit. During this unit I have had to look at not just what we are learning currently but equations that we learned in the beginning of the year. I had much larger set of possibilities from which I had to choose the rights way to solve the problem. I think I have gotten better at doing this and I look foreword to more opportunities to hone my problem solving skills as the year progresses.

Monday, December 7, 2009

Inertia

Part A

In this unit I learned about the first of Newton's three laws of Motion. Newton's first law is stated as: "An object at rest tends to stay at rest and an object in motion tends to stay in motion with the speed and in the same direction unless acted upon by an unbalanced force."Derived from Newton's first law is the concept of translational equilibrium. Translational equilibrium only occurs when the vector sum of the forces acting upon a body is zero, this is a statement of Newton's first law of Motion for objects at rest or moving in a straight line at a constant velocity. We can use translational equilibrium to calculate the magnitude of the forces acting on an object because equilibrium can find out the sum of the forces in each axis and set them equal to zero (because the vector sum of the forces is zero). Using this concept you can solve problems, for example if you are given the applied force, the mass, and the angle of the applied force to the horizontal you can calculate ∑Fx and ∑Fy and set them equal to zero to obtain the values of the other forces. 


What I had trouble with most was determining the x and y components of certain forces because I couldn't decide whether it should be the F sin theta or F cosine theta. Before, I assumed that the y component would always be sin because it was the vertical component and the x component, which is the horizontal component, would always be cosine. When I did these problems, I realized that the relation was geometric. I found out that if you are calculating the force that is opposite from the angle you use sin (SOH opposite/hypotenuse) and if the you are calculating the component of the force that is adjacent to the angle then you use cosine (CAH adjacent/hypotenuse). Whether to use sin or Cosine has nothing to do with which component you are calculating (x or y, vertical or horizontal), it only has to do with its relation to the angle of the force.

My problem solving skills have drastically improved since the start of the year, and I feel that this unit has also contributed to my ability to look at each problem from a number of different perspectives to find the appropriate solution. At first, the problems seemed very difficult, but as I wrote out my data and drew a FBD I realized that the solution was not as difficult as it initially seemed.


Part B

What we have learned is very important in the real world. For example, forces and angle must be taken into consideration when baby car seats are manufactured. to make sure the baby does not fly foreword when the car is braked, the manufacturers strap the baby into the seat tight enough to offset inertia. Another example is the runaway truck ramps on free ways with steep gradients. If a truck is moving on a plane that is inclined downwards and its brakes fail it continue in motion unless and unbalanced force acts on it. The emergency ramp serves as that unbalanced force because it is slanted upwards enough to slow the truck to a stop.







runaway-truck-ramp.jpg
an example of a runaway truck ramp

Thursday, November 12, 2009

Content: Free Fall (awesome video with Galileo played by a box dude thingy)



This video is about Galileo coming back from the dead explaining free fall to a confused physics student. The reason he is a weird box man is beacuse the undead always look funny.

Friday, November 6, 2009

Thursday, October 29, 2009

My Ghandi Voki

¿wordle?