good to get back to work . . .


PhySP18SS6.2.2 First decent angle problem. Notice that everytime you have a force at an angle it is the hypotenuse of a right triangle. You should color in any of those triangles. You won’t ever use the hypotenuse in your calculations (unless you are doing headtotail) You will just use the Fx and Fy legs.


PhySP18SS6.2.3 5b and 5c are simply orange equations


PhySP18SS6.2.4 This is from one of the false statements . Remember, Newton’s 3rd law tells you that the forces in a collision between two bodies are equal and opposite, but since F=ma and the masses are different, the accelerations HAVE to be different to keep the forces equal (and opposite).


PhySP18SS6.2.5 Dr. Strauss talked about this crazy notion of considering Energy as the same as mass and he said that that is how all the High Energy Physicists see mass. So, they change the famous E=mc^2 equation into E/c^2 = m; or just say E = mass as long as you change the units of mass from kilograms to Electronvolts. It is an energy unit, however you can use it as a mass unit too because of the famous Einstein relation E=m*c^2. If you are given a mass in eV, you just have to use that formula to get the corresponding mass in real mass units. Strictly speaking it’s a unit of energy. But using m=Ec2, you can convert energy into mass. Operating, we get 1eV/c2=1.78⋅10−36kg. (The c2 is usually ommited.)


PhySP18SS6.2.6 The number of oscillations of the inertial balance is inversely proportional to the mass that is set on the balance because it takes a lot of force to cause the mass on the balance to change directions. The cool thing about an inertial balance os that you would get the same results anywhere in the universe you took the balance as long as the gravitational attraction of the nearest big body was perpendicular to the balance. Since the movement is sideways, gravity play no role. That is why it is called an INERTIAL balance.


PhySP18SS6.2.7 From one of the false statements. When two steel balls of different masses hit each other and bounce off, the forces are equal and opposite, but the accelerations are definitely different since they are inversely related to their mass.


PhySP18SS6.2.8 Same deal as previous slide.


PhySP18SS6.2.9 THis is also from the false statements. Objects near the surface of the earth all have the same acceleration, not the same gravitational force (which we call their weight). See next:


PhySP18SS6.2.10 The Basketball has ten times the greavitational force (weight) oulling it down to earth as the tennis ball, BUT . . . it also has ten times the resistance to move. Therefore the two objects move at the same rate of acceleration in a vacuum.


PhySP18SS6.2.11 Since mass and acceleration are multiplied together to give force in Newton’s 2nd law, they are INVERSELY proportional.


PhySP18SS6.2.12 SO the equation of impulse basically just comes from Newton’s Original 2nd Law.


PhySP18SS6.2.13 Some impulse information


PhySP18SS6.2.14 One type of impulse problem


PhySP18SS6.2.15 . . .


PhySP18SS6.2.16 Impulse is also the area under a Force vs. Time graph.


PhySP18SS6.2.17 . . .


PhySP18SS6.2.18 nTheis is the Impulse graph for a typical symmetric elastic collision. We represent the curve as a triangle because we don’t do Calculus.


PhySP18SS6.2.19 Our approximations


PhySP18SS6.2.20 our approximations


PhySP18SS6.2.21our approximations


PhySP18SS6.2.22 A graphical Impulse problem


PhySP18SS6.2.23 finishing the previous screenshot.


PhySP18SS6.2.24 6.5.8


PhySP18SS6.2.25 Prob 6.6.1


PhySP18SS6.2.26 Problem 6.6.2


PhySP18SS6.2.27 Problem 6.6.3


PhySP18SS6.2.28 Problem 6.6.5


PhySP18SS6.2.29 Problem 6.7.3


PhySP18SS6.2.30 Problem 6.7.3 more complete


PhySP18SS6.2.31 Problem 6.7.6


PhySP18SS6.2.32 Problem 6.7.6
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