Physical Principles of Design

Lecture-1

Monday 13.January.2003

Basic Physical Principles

Basic Physical Principles

• 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).

Length(m); speed(m/s); acceleration (m/s2)

units: Kg m/s2=Newton(N)

Energy: N m=Joule=Kg m2/s2=J

Power: energy/time=J/s

X

V

a

amF

Class #2Take-Away Concepts

1 D E q u a t i o n s o f M o t i o n f o r C o n s t a n t A c c e l e r a t i o n

B a s i c E q u a t i o n s1 . 00 ttavv 2 . 2

02

1000 )tt(a)tt(vxx

D e r i v e d E q u a t i o n s

3 . )tt)(vv(xx 002

10

4 . 202

100 )tt(a)tt(vxx ( c o m p a r e w i t h 2 . )

5 . 020

2 xxa2vv

Class #2Problems of the Day

_______1. Which one graph below represents a motion for which it would be incorrect touse equations 1-5 to solve a one-dimensional motion problem – even if youbroke the motion into two time intervals? Note: The respective graphs arestraight line segments and v = velocity, a = acceleration.

A)

v

t B)

v

t

C)

a

t D)

a

t

Class #2Problems of the Day

2. A construction worker on a new high-rise building drops awrench and it falls 78.4 m to the ground. How fast is it movingwhen it hits, assuming no air resistance? Use g = 9.8 m/s2.