CHAPTER 4 FORCES IN 1-D FORCE Force is anything which causes a body to start moving when it is at rest, or stop when it is moving, or deflect once it.

Slides:



Advertisements
Similar presentations
Forces – Chapter 4.
Advertisements

Dr. Steve Peterson Physics 1025F Mechanics NEWTON’S LAWS Dr. Steve Peterson
Force Force is a push or pull on an object The object is called the System Force on a system in motion causes change in velocity = acceleration Force is.
AP Physics Chapter 5 Force and Motion – I.
Newton’s Laws.
NEWTON'S LAWS OF MOTION There are three of them.
Free Body Diagram. Used to show all net forces acting on an object What can an object with a net force of zero be doing?
Force Chapter 6. Force Any push or pull exerted on an object.
Physics Chapter 6 Forces. Newton’s Laws of Motion 1 st Law (Law of inertia) –An object moving at constant velocity keeps moving at that velocity unless.
Forces Ch. 6 Milbank High School. Sec 6.1 Force and Motion ► Objectives  Define a force and differentiate between contact forces and long-range forces.
Chapter 4 Forces and the Laws of Motion. Chapter Objectives Define force Identify different classes of forces Free Body Diagrams Newton’s Laws of Motion.
Chapter 4 Physics. Section 4-1 I. Forces A. Def- a push or pull; the cause of acceleration. B. Unit: Newton Def- amt. of force when acting on a 1 kg mass.
Physics Chp4.
Physical Science: Concepts in Action
Chapter 12 Forces and Motion.
Chapter 6 Force and Motion.
S-24 Define the following terms A. Weight B. Gravity C. Friction
What do you know about forces?
Force and Its Representation
Newton’s Second Law of Motion. Force and Acceleration Force is a push or a pull acting on an object. Acceleration occurs when the VELOCITY of an object.
Chapter 4 Dynamics: Newton’s Laws of Motion
In order to change the motion Of an object, you must apply A force to it.
Notes – Chapter 4 – Forces in One Dimension. Force Force - Any push or pull acting on an object F = vector notation for the magnitude and direction F.
What is a Force? A force is a push or a pull causing a change in velocity or causing deformation.
Sir Isaac Newton Newton’s Laws of Motion Newton’s 1st Law of Motion -An object at rest, will remain at rest, unless acted upon by an unbalanced.
Notes Force. Force is a push or pull exerted on some object. Forces cause changes in velocity. The SI unit for force is the Newton. 1 Newton = 1 kg m/s.
 Define the following terms  A. Weight  B. Gravity  C. Friction S-33 I can explain the relationship between weight, gravity, and friction.
Force & Newton’s Laws of Motion. FORCE Act of pulling or pushing Act of pulling or pushing Vector quantity that causes an acceleration when unbalanced.
A push or a pull on an object is called a force.
Remember!!!! Force Vocabulary is due tomorrow
Chapter 12.  Force: a push or pull that acts on an object  Key Point: a force can cause a resting object to move or it can accelerate a moving object.
FORCE is any push or pull which causes something to move or change its speed or direction.
Newton’s laws of motion Newton’s laws of motion describe to a high degree of accuracy how the motion of a body depends on the resultant force acting on.
The tendency of objects to resist change in their state of motion is called inertia  Inertia is measured quantitatively by the object's mass.  Objects.
Newton’s Laws AP Physics C. Basic Definitions  Inertia  property of matter that resists changes in its motion.  Mass  measurement of inertia  Force.
Force Chapter 6. Force Any push or pull exerted on an object.
Basic Information: Force: A push or pull on an object Forces can cause an object to: Speed up Slow down Change direction Basically, Forces can cause an.
Honors Physics Chapter 4
Forces and the Laws of Motion Chapter 4. Forces and the Laws of Motion 4.1 Changes in Motion –Forces are pushes or pullss can cause acceleration. are.
Test #3 Notes Forces and the Laws of Motion Circular Motion and Gravitation Chapters 4 and 7.
Forces & Motion. What is a Force? Force: push or pull Unit: Newton (N)  Kg x m/s 2 Vector: has both magnitude & direction.
Forces. I. Section 1 A. Newton- (N) the SI unit for the magnitude of a force. Also called weight. B. Force- a push or a pull. Described by its magnitude.
FORCES Chapter 5. Mechanics The study of Motion Isaac Newton, 1600’s The father of mechanics.
Forces & Motion. Motion A change in the position of an object Caused by force (a push or pull)
Forces and Newton’s Laws of Motion. A force is a push or a pull. Arrows are used to represent forces. The length of the arrow is proportional to the magnitude.
CHAPTER 4 FORCES. Force  What do you think a force is?  It is a push or pull on an object  A force is a vector quantity.
1 st Law Law of Inertia.  An object at rest tends to stay at rest and an object in motion tends to stay in motion with a constant velocity and unless.
Concept of a Force. What is a Force? Usually think of a force as a push or pull. A force can deform, stretch, rotate, or compress a body. It makes an.
1 Physics: Chapter 4 Forces & the Laws of Motion Topics:4-1 Changes in Motion 4-2 Newton’s First Law 4-3 Newton’s Second & Third Laws 4-4 Everyday Forces.
Forces and Motion Forces I. What is a force? A. The study of force is a very important part of physics. B. A push or pull that acts on an object.
“Law of Acceleration” Forces can be BALANCED or UNBALANCED Balanced forces are equal in size (magnitude) and opposite in direction UNbalanced.
Chapter 8 Forces & Motion.
A push or a pull on an object is called a force.
Forces Chapter 5.
Forces Force- a push or pull
Forces.
Force and Motion.
Sign in Handouts Phones up
FORCES AND NEWTON’S LAWS OF MOTION
CHAPTER 4 FORCES IN 1-D.
Newton’s Laws of Motion
Sir Isaac Newton
Forces Chapter 4.
Ch 4 Forces in One Dimension
Forces Unit 9 Lecture.
Forces and Motion Investigate and apply Newton’s three laws of motion.
Forces & Motion.
The study of why objects move.
Forces & Newton’s Laws of Motion
Forces.
Presentation transcript:

CHAPTER 4 FORCES IN 1-D

FORCE Force is anything which causes a body to start moving when it is at rest, or stop when it is moving, or deflect once it is moving. Force is a push or pull on an object.

KINDS OF FORCES Gravitational Force: is an attractive force that exists between all objects. It is a weak force. Electromagnetic Force: consists of electric & magnetic forces. These forces give materials their strength, their ability to bend, squeeze, stretch, or shatter.

KINDS OF FORCES Nuclear Force: hold particles in the nucleus together. It is the strongest kind of force. Weak Force: is a form of electromagnetic force and is involved in the radioactive decay of some nuclei.

TYPES OF FORCES Weight (W): A field force due to gravitational attraction between two objects. (Ex. You and Earth) Normal Force (F N ): The contact force exerted by a surface on an object. (Ex. You and the floor)

TYPES OF FORCES Friction (F f ): A contact force that acts to oppose sliding motion between surfaces. (Ex. Sliding a box across carpet) Tension (T): The pull exerted by a string, rope or cable when attracted to a body and pulled taut. (Ex. A climber hanging from a rope)

TYPES OF FORCES Spring Force (F S ): A restoring force; the push or pull a spring exerts on an object. Thrust (F trust ): A general term for the forces that move objects such as rockets, planes, cars and people.

Newton’s First Law states that an object at rest remains at rest, and an object in motion continues moving in a straight line at constant speed, unless acted upon by an unbalanced force. Inertia is the tendency of an object to remain at rest or to keep moving in a straight line at constant speed.

Newton’s Second Law states that a net force acting on an object causes the object to accelerate in the direction of the force. A larger mass requires a greater force than a smaller mass would require to achieve the same acceleration.

If an object has a net force exerted on it, it will accelerate. Force and acceleration both have direction and magnitude. The acceleration is in the same direction as the force causing it. (Ex. Picking up a stack of books)

One Newton: is the amount of force needed to accelerate an object with a mass of 1 kg at an acceleration of 1 m/s 2. 1 N = 1 kg x 1 m / s 2 F = m x a F = Force (N) m = mass (kg) a = acceleration (m / s 2 )

EXAMPLE 1 What is the net force required to accelerate a 1500 kg race car at 3 m/s 2. What is the net force required to accelerate a 1500 kg race car at 3 m/s 2.

EXAMPLE 2 An artillery shell has a mass of 55 kg. The shell is fired from a gun, leaving the barrel with a velocity of 770 m/s. The gun barrel is 1.5 m long. Assume the force, and thus the acceleration of the shell is constant while the shell is in the gun barrel. What is the force on the shell while it is in the gun barrel?

FALLING OBJECTS Near the Earth’s surface gravity causes all falling objects to accelerate at 9.8 m/s 2. Weight of an object W, is the force of gravity acting on its mass. W = m x g

W = weight (N) m = mass (kg) g = acceleration due to gravity (9.8 m/s 2 ) (9.8 m/s 2 )

EXAMPLE 3 Find the weight of a 2.26 kg bag of sugar. (g=9.8 m/s 2 ). Find the weight of a 2.26 kg bag of sugar. (g=9.8 m/s 2 ). The direction of the weight is downward. The direction of the weight is downward.

ELEVATORELEVATORELEVATORELEVATOR PROBLEMSPROBLEMSPROBLEMSPROBLEMS A person is standing on a scale in the elevator. What does the scale read?

STEPS TO SUCCESS 1. Draw Free-Body Diagram 2. Consider what’s happening 3. Follow the GUESS method 4. Remember the scale reads normal force 5. Put a box around your final answer

WHAT’S HAPPENING A) Elevator is at rest B) Elevator is moving up C) Elevator is moving down D) Elevator is in free fall 

A) Elevator is at rest Elevator acceleration is zero (a=0) The two opposing forces are the normal force and weight of the object. N – W = 0  N = W (zero indicates no accel) N W Scale reads W of object

B) Elevator is moving up Elevator has acceleration The person on the scale is supported by the scale so they are balanced, however we must take the acceleration of the elevator into consideration N W a

REMEMBER N W a The elevator has to exert a force to move the object, the scale reading is affected by the elevator’s acceleration N – W = ma  N = ma + W (accel is positive here)

C) Elevator is moving down Elevator has acceleration The person on the scale is supported by the scale so they are balanced, however we must take the acceleration of the elevator into consideration N W a

AGAIN N W a The elevator has to exert a force to move the object, the scale reading is affected by the elevator’s acceleration N – W = - ma  N = W – ma (accel is negative here)

D) Elevator is in free fall Example of when the support cable breaks  Elevator’s acceleration is equal to gravity in this case N – W = -mg  N = W – mg (where W = mg N = mg – mg N = 0 N W a

Air Resistance: is the force air exerts on a moving object. This force acts in the opposite direction to that of the objects motion. Air resistanceForce of Gravity

AIR RESISTANCE Air resistance pushes up as gravity pulls down. Air resistance pushes up as gravity pulls down. The amount of air resistance depends on the size, speed, shape, and density of the object. The amount of air resistance depends on the size, speed, shape, and density of the object. The larger the surface area the greater the amount of air resistance on it. The larger the surface area the greater the amount of air resistance on it.

Newton’s Third Law of Motion states that when one object exerts a force on a second object, the second object exerts a force on the first that is equal in magnitude but opposite in direction.

STATIC FRICTION is the force that opposes the start of motion. KINETIC FRICTION is the force between surfaces in relative motion. Kinetic Friction < Static Friction The static friction of an object is greater than its kinetic friction FRICTION

1 BODY SYSTEMS IN 1-D W N F Pushing down on an object with a force (F)

W N F In the y- direction: N – W – F = 0 object is not moving so forces balance

1 BODY SYSTEMS IN 1-D W T Consider an object hanging from a chain.

W T In the y- direction: T – W = 0  T = W object is not moving so forces balance

2 BODY SYSTEMS IN 1-D Consider two objects hanging over a pulley. m1m1 T m2m2 T a

m1m1 T m2m2 T a T a m1m1 m1gm1g Object 1 T m2m2 m2gm2g a Object 2

T m2m2 m2gm2g T m1am1a m1m1 m1gm1g m 1 a = m 1 g – T m 2 a = T – m 2 g m2am2a