Force and Motion-II
1. If you send a book sliding down a horizontal surface, the
book will finally slow down and stop.
2. If you push a heavy crate and the crate does not move,
then the applied force must be counteracted
Center of Mass
9.2 The Center of Mass
The center of mass of a
system of particles is the
point that moves as
though (1) all of the
systems mass were
concentrated there and
(2) all external forces
were applied there.
When a capacitor is charged, its plates have charges of equal magnitudes but opposite signs: q+ and
q-. However, we refer to the charge of a capacitor as being q, the absolute value of these cha
Rolling, Torque, and
11.2 Rolling as Translation and
Although the center of the object moves in a straight line parallel to the surface, a point on the rim
certainly does not.
This motion can be studied by tre
1. The x and the y components of a vector a lying on the xy plane are given by
ax = a cos ,
a y = a sin
where a = | a | is the magnitude and is the angle between a and the positive x axis.
(a) The x component of a is given by ax = a cos
23.1 What is Physics?:
Gauss law relates the electric fields at points on a
(closed) Gaussian surface to the net charge
enclosed by that surface.
Gauss law considers a hypothetical (imaginary) closed
surface enclosing the charge distr
Motion in two and three
4.2 Position and Displacement
The position of a particle can be described by a
position vector, with respect to a reference
The displacement of a particle is the change of
Kinetic Energy and Work
7.2 What is Energy?
Energy is a scalar quantity associated with
the state (or condition) of one or more
1. Energy can be transformed from one type to another and
10.2 The Rotational Variables
A rigid body is a body that can
rotate with all its parts locked
together and without any change
in its shape.
A fixed axis means that the
rotation occurs about an axis that
does not move.
Figure skater Sa
Induction and Inductance
30.2: First Experiment:
1. A current appears only if there is relative motion
between the loop and the magnet (one must move
relative to the other); the current disappears when
the relative motion between them ceases.
Potential Energy and
Conservation of Energy
8.1 Potential Energy
Technically, potential energy is energy that
can be associated with the configuration
(arrangement) of a system of objects that
exert forces on one another.
Some forms of potential
Electromagnetic Oscillations and
31.2: LC Oscillations, Qualitatively:
In RC and RL circuits the charge, current, and potential
difference grow and decay exponentially.
On the contrary, in an LC circuit, the charge, current,
1. The greatest deceleration (of magnitude a) is provided by the maximum friction force
(Eq. 6-1, with FN = mg in this case). Using Newtons second law, we find
a = fs,max /m = sg.
Equation 2-16 then gives the shortest distance to stop: |x| = v2/
Force and Motion-I
5.2 Newtonian Mechanics
Newtonian Mechanics does not hold good for all situations.
1. Relativistic or near-relativistic motion
2. Motion of atomic-scale particles
5.3 Newtons First Law
1. We are only concerned with horizontal forces in this problem (gravity plays no direct
role). We take East as the +x direction and North as +y. This calculation is efficiently
implemented on a vector-capable calculator, using magnitude-angle n
1. We use Eq. 9-5 to solve for ( x3 , y3 ).
(a) The x coordinate of the systems center of mass is:
m1 x1 + m2 x2 + m3 x3 (2.00 kg)(1.20 m) + ( 4.00 kg )( 0.600 m ) + ( 3.00 kg ) x3
m1 + m2 + m3
2.00 kg + 4.00 kg + 3.00 kg
= 0.500 m.