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.
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.
an example of a runaway truck ramp