Physical Principles of Design
Lecture-1
Monday 13.January.2003
Basic Physical Principles
Basic Physical Principles
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Motion and Acceleration
Static Equilibrium
Properties of Fluids
Temperature and Heat
Strength of Materials and Elasticity
Electromagnetic Properties and Light
Optics and Images
The SI System of Units
a.k.a. “The Metric System”
a.k.a. MKSA
M for meter, K for kilogram;S for second, A for
ampere.
Other units(e.g. Joule,Newton) are derived from
these.
“Always stick with SI units and everything will
come out ok.”
Specific Units
Length: meter(m); Time: second(s); Mass: kilogram(kg).

X 

Length(m);

F  ma

V 
speed(m/s);
units: Kg m/s2=Newton(N)
Energy: N m=Joule=Kg m2/s2=J
Power: energy/time=J/s

a
acceleration (m/s2)
Class #2
Take-Away Concepts
1D Equations of Motion for Constant Acceleration
Basic Equations
1. v  v 0  a  t  t 0 
2. x  x 0  v 0 ( t  t 0 )  2 a ( t  t 0 )
1
2
Derived Equations
1
x

x

( v 0  v)(t  t 0 )
3.
0
2
1
2
x

x

v
(
t

t
)

a
(
t

t
)
4.
(compare with 2.)
0
0
0
2
5. v  v 0  2a x  x 0 
2
2
Class #2
Problems of the Day
_______1.
Which one graph below represents a motion for which it would be incorrect to
use equations 1-5 to solve a one-dimensional motion problem – even if you
broke the motion into two time intervals? Note: The respective graphs are
straight line segments and v = velocity, a = acceleration.
v
A)
v
t
B)
a
C)
t
a
t
D)
t
Class #2
Problems of the Day
2. A construction worker on a new high-rise building drops a
wrench and it falls 78.4 m to the ground. How fast is it moving
when it hits, assuming no air resistance? Use g = 9.8 m/s2.