1. Introduction to Biophysics
Hanna Trębacz
2015/2016
I-st semester; Lecture #1

2. Basic information Introduction to biophysics is a two-semester course
Teaching will consist of:
Lectures (18 hours)
Problem classes (72 class hours).
Written work (12 homeworks)
Learning outcomes
After the course, the student should:
formulate, analyze physical situations and problems using the language and approaches of physics;
know how to use basic calculus in a physical situation or problem
understand the role of physics in medicine.
 Recommended book
College Physics, Willson Jerry D., Buffa Anthony J., Prentice Hall,

3. Basic information The schedule for each semester is :
Weeks 1, 2, 3: one lecture + one lab (3 class hours each)
Week 4 : a review session (during the lecture) + TEST (during the lab)
Weeks 5, 6, 7: one lecture + one lab
Week 8 : a review session + TEST
Weeks 9, 10, 11: one lecture + one lab
Week 12 : a review session + TEST
The final exam will cover material from the whole two semesters.
Detailed Rules and Regulations on :

4. Why physics ?
Physics
is the science that gives the general analysis of nature, conducted in order to understand how the world behaves.

5. The role of physics in life sciences
To apply physical theories based on fundamental laws of nature to understanding of biological systems.
To relate some of the concepts in physics to living system, in order to predict the behavior of these systems in different external and internal conditions.
To give a basis for medical engineering

6. Why physics ?

7. During our course of biophysics you will see that many biological systems can be analyzed quantitatively and that this analysis can be very useful.
Especially, we will try to show you that physics has two important areas of application in medicine –
physics of the body (of physiology)
and the physics of instruments used for diagnosis and therapy.

8. Why you need to know basic calculus
Physics is more quantitative than most other sciences.
Physical definitions, models and theories can often be expressed using mathematical relations.
That is, many of the observations of experimental results in physics are numerical measurements. Most of the theories in physics use mathematics to express their principles. Most of the predictions from these theories are numerical.

9. The seven base units of the SI
Name of unit (abbr.)
Property measured
meter (m)
length
kilogram (kg)
mass
second (s)
time
ampere (A)
electric current
kelvin (K)
temperature
mole (mol)
amount of substance
candela (cd)
luminous intensity

10. Approximate values of some time intervals
Time (s)
Age of the universe
5 x 10 17
Age of the earth
1.3 x 10 17
Age of human civilization
2 x 10 11
Average age of a college student
6.3 x 10 8
One day
8.6 x 10 4
Time between normal heartbeats
8 x 10 -1
Time it takes light to traverse the eye
10 -10

11. Denary notation and prefixes
Power
Prefix
Abbreviation
10 -15
femto f
10 -12
pico p
10 -9
nano n
10 -6
micro μ
10 -3
milli m
10 -2
centi c
10 -1
deci d
10 3
kilo k
10 6
mega M
10 9
giga G
10 12
tera T

12. what we sOuld remember about
Examples of nonstandard units in use :
Time – hour; 1 hr = 3600 s
Volume - liter; 1L = 10-3m3
How to express quantities using
range of magnitude
How to express result of calculations
significant figures
The number of significant figures of a numerical quantity is the number of reliably known digits it contains.
The result of calculations can be no more accurate than the least accurate quantity used.

13. Uncernteinty and Precision of a measurement
Measured number is not an exact number - All real measurements of quantities have some degree of uncertainty
Source of uncertainty - inaccuracy of the result caused by limited precission of the equipement and methods used during measurements
Precision (degree of inaccuracy) – usually given as a percent of a measured value

14. uncertainty and Precission of a measurement - An Example:
mass of an object is measured to be 2.38 g
observer A : uncertainty of the measurement is 0.01g
The result shuld be expressed (2.38±0.01) g
The true value lies between 2.37 g and 2.39 g.
Precision of the measurement ( percentage of the uncertainty in the result obtained)
Precision is (0.01 g : 2.38 g) x 100% = 0.42%

15. Vectors
Vector –a quantity that has magitude and direction and can be represented by a directed line segment.
The length of the segment represents the magnitude and the orientation in space represents the direction. A A A

16. Vectors A
D = 2 x A
D = 3 x A

17. Vectors A B -B A B
C = A + B -B A
C = A - B

18. How to add two vectors B A B -B A C = A + B C = A - B A A C = A + B

19. two perpendicular vectorsB
C = A + B B
C = A + B

20. Two perpendicular vectors in a Cartesian coordinate system

21. Kinematics Basic terms: Displacement Speed Velocity Acceleration
a branch of physics which describes the motion of objects
Basic terms:
Displacement
Speed
Velocity
Acceleration

22. Types of motion Uniform motion in one dimension
Accelerated motion in one dimension
Two dimensional motion
Circular motion

23. Motion in one dimension
The average velocity , v,
of the particle, is defined as the ratio of its displacement in a given direction, Δx, and the time interval, Δt: X Xi Xf
Instantaneous velocity, v ,
equals the limiting value of the ratio
Δx/Δt as Δt approaches zero.

24. Uniform motion in one dimension
A body to be in the uniform motion must be moving in the straight line path and cover equal distance in equal interval of time
In a uniform motion distance covered is proportional to time

25. Accelerated motion in one dimension
The average acceleration of the particle in the time interval is defined as the ratio of the change in the velocity and this time interval
Instantaneous acceleration, a ,
equals the limiting value of the ratio
Δv/Δt as Δt approaches zero

26. Motion with constant acceleration
v = vi+at
Velocity changes linearlly with time
vaver = (vf + vi)/2
In an accelerated motion ( at constant acceleration) distance covered depends on the time squared.
x = vit + at2/2 (vi  v0)

27. SI units of velocity and acceleration (derived SI units)

28. Two dimensional motion
At the start, velocity of the ball is equal to 10 m/s and the angle is equal to 45 deg find x and y components of the velocity.

29. Thank you
See you next week!