Portfolio Journal

                       Physics Hints From Knowledge Gained in Physics 30
     1.   Always pay attension to direction in vector questions and make sure to draw a diagram to
     show these directions.
     2.   Graphs: Be aware of the slope and area under the curve
     3.   Kinematics Equations: MEMORIZE!
     4.   Perpendicular components of vectors do not effect each other (Projectile motion)
     5.   Objects never drop like in cartoons they always drop in parabolic arcs.
     6.   Negatives and Positives merely refer to directions
     7.   In labs, repetition increases accuracy (If all the trials are done with accuracy)
     8.   Newton’s Laws
          1. An object in motion (uniform velocity, straight line) or at rest tends to stay in motion
     or at rest unless otherwise acted by an unbalanced force
    2. F=ma
          3. When one object exerts a force on a second object, that second object exerts an equal
     and opposite force on the first. (For every reaction there is an equal and opposite
     reaction)
     9.   Use freebody diagrams to clarify forces and their directions.
     10.  Friction: Opposes motion.
     11.  Remember weight is a force
    Metric units weighs 780N mass is 80 kg
     12.  Remember uniform velocity means no acceleration.
     13.  Acceleration in a circle   
    a=v2 
         r
     14.  All massive bodies exert an attractive force between each other
    F=Gm1m2                      G= 6.67(10-11 Nm2/kg2)
            r2
     15.  Momentum = “A quantity of motion”
          P=MV

     16. 
Momentum is conserved, velocity is not.
     17.  Orbits! Fg=Gm1m2             m1=mass of orbiting body        
                          r2
    Fc=m1v2               Fc=Fg
            r

     18.  Impulse is the change of momentum
    Pf-Pi=F(change in t)
    I=F(change in t)

19.      Work is a product of force and displacement in the direction of the force. Work is a
Scalar.
    N(m)=N*m                  Kgm2/s2=joules

     20.  Energy causes work to be done.

     21.  Gravitational potential energy (Epot)
    E=mg(change in height)
     22.  Kinetic Energy (Ek)
    Ek=1/2mv2
     23.  Potential to Kinetic: energy is preserved
    Etot=Epot+Ek