Biophysics First Level Quiz

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Questions and Answers

What is the unit of rate change of velocity in cgs?

cm.s−2 (correct)

m.s−2

kg.s−2

g.s−2

What is the dimension of force gradient?

MLT−1

ML2T−2

MLT−2

MT−2 (correct)

What is the unit of force gradient in MKS units?

g.s−1

Kg.s−2 (correct)

g.s−2

Kg.s−1

Which of the following best describes numeric constants?

Have no dimensions and no units Signup and view all the answers

What is the expression for the gradient of a quantity?

Quantity/Distance Signup and view all the answers

What is the primary purpose of dimensional analysis in the context of mathematical equations?

To ensure equations have the correct dimensions Signup and view all the answers

Which of the following equations describes a linear relationship in physics according to dimensional analysis?

X = V0 t + a t^2 Signup and view all the answers

In the equation X = V0 t + a t^2, what does V0 represent?

The initial velocity Signup and view all the answers

What type of term is a t^2 in the equation X = V0 t + a t^2?

Quadratic term Signup and view all the answers

Which dimension does the left-hand side of the equation X = V0 t + a t^2 represent?

Displacement Signup and view all the answers

What is the formula for calculating density?

ρ = m/V Signup and view all the answers

What are the correct units for density in the context provided?

ML−3 Signup and view all the answers

What is the dimensional formula for density?

ML−3 Signup and view all the answers

In the equation ρ = m/V, if the mass doubles while the volume remains constant, what happens to the density?

Density doubles Signup and view all the answers

Which of the following represents a common mistake in understanding density?

Density is always constant for a substance Signup and view all the answers

What is the unit of energy in the given context?

Joule Signup and view all the answers

How is energy measured in the cgs system?

Gram-centimeter squared Signup and view all the answers

What calculation is represented by the term '1000 x 10000 x 10^7'?

Energy in cgs units Signup and view all the answers

Which of the following describes the relationship between Joules and cgs units?

Joules are larger than cgs units Signup and view all the answers

What dimensional formula is used for energy according to the provided content?

g.cm^2 Signup and view all the answers

What is the formula for acceleration?

a = v/t Signup and view all the answers

In the formula for force, F = m × a, what do the symbols represent?

Force is mass times acceleration Signup and view all the answers

What are the SI units of acceleration?

m/s² Signup and view all the answers

What are the dimensional units for force?

MLT−2 Signup and view all the answers

What does the symbol 'v' represent in the acceleration formula?

Velocity Signup and view all the answers

What is the relationship between Joules and ergs?

1 Joule = 10^7 ergs Signup and view all the answers

What is the formula for calculating velocity?

Velocity = x/t Signup and view all the answers

Which dimension represents velocity?

LT^-1 Signup and view all the answers

What is the density formula?

Density = m/V Signup and view all the answers

What unit is equivalent to 1 Kg in g?

10^3 g Signup and view all the answers

What is the definition of a gradient?

Change in quantity with respect to distance Signup and view all the answers

Which statement about the refractive index is true?

It is dimensionless and has no unit Signup and view all the answers

The dimension of rate change of velocity is represented as?

LT^-2 Signup and view all the answers

To convert Km/h to m/s, which factor is used?

0.27778 Signup and view all the answers

What is the density dimension?

ML^-3 Signup and view all the answers

Study Notes

Introduction to Biophysics

Course: Biophysics
Level: First Level
Year: 2024-2025
Instructors: Dr. Nermin Ali, Dr. Enas Lotfy
Course Code: FAC-104

Dimensions and Units

SI Units: A standardized system of units
Basic Quantities: Length (L), Mass (M), Time (T), Electric Current (I), Temperature (Θ), Amount of substance (N), Luminous intensity (J)
Derived Quantities: Calculated from basic quantities (e.g., velocity, acceleration, force, pressure).
Scalar Quantities: Described only by magnitude (e.g., price, age, speed).
Vector Quantities: Described by both magnitude and direction (e.g., force, velocity)
Units: Standard measurements for dimensions (e.g., meters for length).

Basic Definitions

Basic Quantity: A quantity that cannot be expressed in terms of other quantities.
Basic quantities include: Length, Mass, Time.
Other basic quantities include: Electric current, Luminous intensity, mole, temperature

Derived Quantities

Derived Quantity: A quantity that can be expressed in terms of more than one basic quantity.
Example quantities: Velocity, acceleration, force, pressure

Scalar Quantities

A quantity defined only by its magnitude.
Examples include: price, age, speed.

Vector Quantities

A quantity defined by both magnitude and direction.
Examples include: force, velocity.

Difference Between Dimension and Unit

Dimension: Represents the physical nature of a quantity (e.g., length).
Unit: Represents the standard for measuring a dimension (e.g., meters).
Dimension defines what is being measured, while the unit defines how it is measured.

SI Base Quantities and Units

Quantity	SI Unit	Symbol
Length	Meter	m
Mass	Kilogram	kg
Time	Second	s
Electric Current	Ampere	A
Temperature	Kelvin	K
Amount of substance	Mole	mol
Luminous intensity	Candela	cd

Area and Volume

Area: Length × Width, dimension [L²]
Volume: Length × Width × Height, dimension [L³]

Dimension and Units of Basic and Derived Quantities

Provides formulas and dimensions for various quantities (mass, length, time, area, volume, velocity, acceleration, force, pressure, viscosity, density.) and their units in MKS and CGS.

Converting Quantities from One System to Another

Explaining how to convert quantities (like force, energy and velocity) from one system like MKS (meter, kilogram, second) to others like CGS (centimeter, gram, second).
- Shows the conversions

Ratio, Rate, Gradient

Ratio: Comparison of similar quantities.
Rate: Change in a quantity over time.
Gradient: Change in a quantity over distance.

Refractive Index

A ratio representing the change in the velocity of light as it passes from one medium to another.
It has no dimensions and no units.

Velocity

The rate of change of displacement with respect to time.
Dimension: LT^-1
Units: m/s (MKS) or cm/s (CGS)

Density

The ratio of mass to volume, dimension: ML⁻³
Units: kilograms per cubic meter (MKS) or grams per cubic centimeter (CGS)

Difference between Numeric and Physical Constants

Numeric constant: Does not have dimensions nor units
Physical constant: Has both dimension and units.

Dimensional Analysis

A technique to check the consistency of equations.

Gravitational Constant

The constant in Newton's law of universal gravitation.
Dimension: M^-1L³T^-2.
Unit in MKS: kg^-1m³s^-2.
Unit in CGS: g^-1cm³s^-2

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Description

Test your knowledge on the introduction to biophysics, focusing on dimensions, units, and basic quantities. This quiz covers essential concepts such as scalar and vector quantities, and the SI units fundamental to the field. Dive into the core definitions that will enhance your understanding of biophysics.