PHYS 1111 Studio Physics Fall 2009
Summary for Ch1 through Ch 4
Models, Measurements, and Vectors
SI units in Mechanics: Mater (m), Kilogram (kg), and Second (s);
Unit conversion
Scalar (magnitude) and Vector (magnitude and direction);
Vector addition, subtraction, and components; e.g. for two dimensions: A  Ax2  Ay2 tan   Ay / Ax ;
Graphic expressions (triangle and parallelogram methods).
Motion along a Straight Line
Distance and Displacement, Speed and Velocity, and Acceleration
Kinematics equations for constant acceleration:
v  v0  at
1
x  x0  v0t  at 2
2
2
2
v  v0  2a ( x  x0 )
1
x  (v  v0 )t
2
Typical example, freely falling bodies, a = 9.8 m/s2 = g (“+” or “-“ sign depends on your coordinates)
Motion in a Plain
Displacement, velocity, and acceleration are vectors that can be resolved into two components. Each
component will follow the kinematics equations in 1-D.
Projectile motion: horizontal, vertical, height, range, initial velocity, and etc.
v02 sin( 2 0 )
g
2
y  tan  0 x  2
x
and R 
2v0 cos 2  0
g
Uniform circular motion: a 
v2
; radial direction, constant magnitude.
R
Newton’s Laws of Motion
Law of inertia, law of motion: F = ma, and action-reaction law
Types of forces: gravitational force, normal force, friction forces (static and kinetic); and tension
FREE BODY DIAGRAM
Equilibrium condition for a point mass: F = 0 or Fx = 0, Fy = 0, and Fz = 0.
Weight w = mg.