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- Introduction to applied math
- Dynamics: force and newton's
- Newton’s second law of motion:
Newton’s second law of motion is more than a definition; it is a relationship among acceleration, force, and mass. It can help us make predictions. Each of those physical quantities can be defined independently, so the second law tells us something basic and universal about nature. The next section introduces the third and final law of motion.
Section summary
- Acceleration,
, is defined as a change in velocity, meaning a change in its magnitude or direction, or both.
- An external force is one acting on a system from outside the system, as opposed to internal forces, which act between components within the system.
- Newton’s second law of motion states that the acceleration of a system is directly proportional to and in the same direction as the net external force acting on the system, and inversely proportional to its mass.
- In equation form, Newton’s second law of motion is
.
- This is often written in the more familiar form:
.
- The weight
of an object is defined as the force of gravity acting on an object of mass
. The object experiences an acceleration due to gravity
:
- If the only force acting on an object is due to gravity, the object is in free fall.
- Friction is a force that opposes the motion past each other of objects that are touching.
Conceptual questions
Which statement is correct? (a) Net force causes motion. (b) Net force causes change in motion. Explain your answer and give an example.
Why can we neglect forces such as those holding a body together when we apply Newton’s second law of motion?
Explain how the choice of the “system of interest” affects which forces must be considered when applying Newton’s second law of motion.
Describe a situation in which the net external force on a system is not zero, yet its speed remains constant.
A system can have a nonzero velocity while the net external force on it
is zero. Describe such a situation.
A rock is thrown straight up. What is the net external force acting on the rock when it is at the top of its trajectory?
(a) Give an example of different net external forces acting on the same system to produce different accelerations. (b) Give an example of the same net external force acting on systems of different masses, producing different accelerations. (c) What law accurately describes both effects? State it in words and as an equation.
If the acceleration of a system is zero, are no external forces acting on it? What about internal forces? Explain your answers.
If a constant, nonzero force is applied to an object, what can you say about the velocity and acceleration of the object?
The gravitational force on the basketball in
[link] is ignored. When gravity
is taken into account, what is the direction of the net external force on the basketball—above horizontal, below horizontal, or still horizontal?
Problem exercises
You may assume data taken from illustrations is accurate to three digits.
A 63.0-kg sprinter starts a race with an acceleration of
. What is the net external force on him?
If the sprinter from the previous problem accelerates at that rate for 20 m, and then maintains that velocity for the remainder of the 100-m dash, what will be his time for the race?
Questions & Answers
the study of living organisms and their interactions with one another and their environments
AI-Robot
HOW CAN MAN ORGAN FUNCTION
the diagram of the digestive system
allimentary cannel
Ogenrwot
They formed in two ways first when one sperm and one egg are splited by mitosis or two sperm and two eggs join together
Oluwatobi
Genetics is the study of heredity
Misack
how does twins formed?
Misack
discuss biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles
the study of living organisms and their interactions with one another and their environment.
Wine
discuss the biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles in an essay form
list any five characteristics of the blood cells
Shaker
lack electricity and its more savely than electronic microscope because its naturally by using of light
advantage of electronic microscope is easily and clearly while disadvantage is dangerous because its electronic. advantage of light microscope is savely and naturally by sun while disadvantage is not easily,means its not sharp and not clear
Abdullahi
cell theory state that every organisms composed of one or more cell,cell is the basic unit of life
Abdullahi
is like gone fail us
DENG
cells is the basic structure and functions of all living things
Ramadan
is organisms that are similar into groups called tara
Yamosa
in what situation (s) would be the use of a scanning electron microscope be ideal and why?
A scanning electron microscope (SEM) is ideal for situations requiring high-resolution imaging of surfaces. It is commonly used in materials science, biology, and geology to examine the topography and composition of samples at a nanoscale level. SEM is particularly useful for studying fine details,
Hilary
cell is the building block of life.
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Source:
OpenStax, Introduction to applied math and physics. OpenStax CNX. Oct 04, 2012 Download for free at http://cnx.org/content/col11426/1.3
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