Unit 2 1D Vectors & Newton’s Laws of Motion. A. Vectors and Scalars.

Slides:



Advertisements
Similar presentations
Unit 4 FORCES AND THE LAWS OF MOTION
Advertisements

FORCE A force is any influence that can change the velocity of a body. Forces can act either through the physical contact of two objects (contact forces:
Dr. Steve Peterson Physics 1025F Mechanics NEWTON’S LAWS Dr. Steve Peterson
Newton’s Laws The Study of Dynamics Isaac Newton Arguably the greatest physical genius ever. Came up with 3 Laws of Motion to explain the observations.
Chapter 4 Forces.
APC -Unit 2. 2 nd Law A 72kg person stands on a scale which sits on a floor of elevator. It starts to move from rest upward with speed v(t) = 3t +
Forces and Free Body Diagrams
Applying Forces (Free body diagrams).
Sliding Friction A force that opposes motion Acts parallel to the
AP Physics Chapter 5 Force and Motion – I.
Constant Force Motion and the Free Body Diagram Teacher Excellence Workshop June 19, 2009.
Newton’s 2nd Law some examples
Laws of Motion Review.
Newton’s Laws of Motion Problems MC Questions
Newton’s Laws of Motion
Force Chapter 6. Force Any push or pull exerted on an object.
Kinematics – the study of how things move Dynamics – the study of why things move Forces (the push or pull on an object) cause things to move Aristotle.
Unit 2 1D Vectors & Newton’s Laws of Motion. A. Vectors and Scalars.
Forces.
AP Physics B Summer Course 年AP物理B暑假班
NEWTON’S SECOND LAW.
SPH3U Exam Review. 1. The property of matter that causes an object to resist changes in its state of motion is called: A. friction B. inertia C. the normal.
C. Newton’s Laws & Forces AP Physics
Newton’s Laws of Motion
AP Physics I.B Newton’s Laws of Motion. B.1 An interaction between two bodies resulting in a push or a pull is a force. Forces are of two types: contact.
Newton’s Laws of Motion
SECOND LAW OF MOTION If there is a net force acting on an object, the object will have an acceleration and the object’s velocity will change. Newton's.
Chapter 4 Dynamics: Newton’s Laws of Motion
What is a Force? A force is a push or a pull causing a change in velocity or causing deformation.
Forces Newton’s Second Law.
– coefficient of kinetic friction
Forces and Free-Body Diagrams
Forces Chapter 4. Forces A push or a pull  Gravitational  Electromagnetic  Weak  Strong.
Remember!!!! Force Vocabulary is due tomorrow
Unit 3 Forces & Motion. Forces Force- an action applied to an object to change its motion(push or pull) Units of lb, N (equal to kg. m/sec 2 ) If forces.
Force A. Force is the push or pull exerted on an object. 1. Contact force: “I can not touch you without you touching me” 2. Field force: ‘How does the.
Introduction to Newton’s Laws
Bellwork Pick up a free-body diagram sheet and begin working on it.
AP Physics C I.B Newton’s Laws of Motion. Note: the net force is the sum of the forces acting on an object, as well as ma.
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.
333 PHYSICS - UNIT 2 FORCES Explanations as to why things occur versus just observation.
Force Chapter 6. Force Any push or pull exerted on an object.
Newton’s First & Second Law AP Physics C. Unit is the NEWTON(N) Is by definition a push or a pull Can exist during physical contact(Tension, Friction,
Unit 3 Forces & Motion. Forces Force- an action applied to an object to change its motion(push or pull) Units of lb, N (equal to kg. m/sec 2 ) If forces.
Newton’s Laws.
Push and Pull Newton’s Laws. Newton’s First Law An object at rest remains at rest, and an object in motion continues in motion with constant velocity.
CP Physics Chapter 4 Newton’s Laws Force Force (F) is a push or a pull Measured in Newtons (N) for SI, pounds (lb) in US. (4.45 N = 1 lb) It has magnitude.
Chapter 4 Dynamics: Aim: How can we describe Newton’s Laws of Motion? © 2014 Pearson Education, Inc.
Laws of Motion Review.
Free Body Diagrams.
Forces Chapter 4. Forces A push or a pull  Gravitational  Electromagnetic  Weak  Strong.
Weight = mass x acceleration due to gravity
332 - Unit 2 1D Vectors & Newton’s Laws of Motion.
Physics and Forces Dynamics Newton’s Laws of Motion  Newton's laws are only valid in inertial reference frames:  This excludes rotating and accelerating.
Mechanics Kinematics Dynamics. Force Fundamental Forces.
-A force that opposes motion -Acts parallel to the surfaces in contact.
I. Newton’s Laws II. Forces III. Free-Body Diagrams Chapter 4: Newton’s Laws and Forces.
The Laws of Motion. Classical Mechanics Describes the relationship between the motion of objects in our everyday world and the forces acting on them Describes.
Sliding Friction A force that opposes motion Acts parallel to the
Dynamics: Newton’s Laws of Motion
Chapter 4 Objectives: 1) Define FORCE; including units.
Applications of Newton’s Laws
Force.
Gravitation, Friction, and Net Force
FORCES.
4-6 Weight – the Force of Gravity; and the Normal Force
Ch. 5 slides Forces.ppt.
Newton’s Laws of Motion Chapters 2,3,6,7
Aim: How do we explain motion along an inclined plane?
Applying Newton’s Laws
Presentation transcript:

Unit 2 1D Vectors & Newton’s Laws of Motion

A. Vectors and Scalars

B. Addition of Vectors & RESULTANT In one dimension, simple addition and subtraction is all that is needed. RESULTANT VECTOR

Aristotle vs Galileo

FORCES NET FORCE

D. TYPES OF FORCES

1) Force of Gravity (Weight) - Without gravity, how can we distinguish between a 1kg and a 2kg mass?

2) Normal Force (Support Force) If the box weighed less, what would happen to the normal force acting on the box?

3) Tension Force

4) Friction Force

E. NEWTON’S LAWS

Newton’s 1st Law of Motion Also called the law of inertia.

Mass

Why do all objects fall at the same rate? (|a|=g=9.8m/s 2 )

Newton’s 3rd Law of Motion

Explain the movement of a rocket using the 3 rd Law.

Question: A loaded school bus hits a bug and kills it. Which body receives the greater force of impact, bug or bus?

Fan for boat with no wind?

Who pulls harder on the rope? Who wins the tug of war?

Force Body Diagrams (FBD) using vectors In order to solve problems involving forces, we need to draw an FBD. A box is dragged by a rope towards the right on a smooth floor. Draw the force vectors on the box.

Newton’s 2 nd Law of Motion Constant velocity equates to what in regards to F net ?

A crane lowers a 1306kg car by a cable with an acceleration of 0.73 m/s 2. The car starts 20.0m above the ground with an initial speed of zero. Example 1 a) What is the tension in the cable? Draw FBD b) How much time will it take the car to reach the ground?

Example 2 A person stands on a bathroom scale in an elevator at rest on the ground floor of a building. The scale reads 836N. As the elevator begins to move upward, the scale reading briefly increases to 935N but then returns to 836N after reaching a constant speed. b) If the elevator was moving at 3.0m/s upwards and then uniformly decelerated to rest in 4.7s, determine the scale reading. a) Determine the acceleration of the elevator.

Example 3: A force of 75N pushes on 2 boxes as shown. The mass of b 1 is 20kg and the mass of b 2 is 35kg. Surface is smooth. a) Determine the acceleration of the two boxes. b) Determine the net force on b 2. c) Determine the net force on b 1. Why is it different?

Example 4: A box (6.2kg) is pulled along a rough, horizontal surface by a rope that is parallel to the surface. The tension in the rope is 23N. The box accelerates from 2.4m/s to 3.6m/s over a distance of 7.5m. Determine the size of the friction force.

Force of Friction (F f ) On a microscopic scale, most surfaces are rough. Force of friction tends to oppose the motion of objects Two Types of Friction: 1) Static Friction (F fs ) 2) Kinetic Friction (F fk )

Friction depends on two things:

In the case of static friction, there is a maximum value at which the static friction force will resist motion between surfaces. This means that if you push a table with 50N of force where maximum static friction is 75N, the table won’t break free. You need to push with just a smidge over 75N where we say you just have to equal maximum static to break free.

The static frictional force increases as the applied force increases, until it reaches its maximum.

What minimum amount of force is needed to start to make a 250N crate move across a floor if the coefficient of static friction is 0.65? Example1

Example2 A physics book is sent sliding across a lab table with a speed of 4.3m/s. If it takes the book 1.6m to stop, determine the value of the coefficient of kinetic friction.

A 5.0kg block is pulled by a tension force of 50.0N along a rough horizontal surface at a constant acceleration. If the coefficient of kinetic friction is 0.40, determine the speed of the block after 3.0s if it starts from rest. Example3

Terminal Velocity Consider a skydiver who steps off a hovering helicopter at high altitude. NOW consider the effect of air resistance (friction) during the fall. d) As the skydiver continues to fall, describe what happens to their speed and acceleration? Why? b) Initially at t=0, what is the acceleration and velocity of the skydiver? a) Initially at t=0, what forces act on the skydiver? c) As the skydiver begins to fall, what happens to the force of air resistance on skydiver? e) Eventually what happens to the speed of the skydiver?

2D Vectors/Forces

A 35.0 kg lawn mower is pushed across a level lawn in a direction of 0.0 . The force exerted on the handle is . Assume friction is negligible. Example 4 (a)Determine the acceleration of the mower. (b)Determine the normal force acting on the lawn mower.

A 67.5-kg sprinter exerts a force of 775N on a starting block which makes a 20 o angle to the ground as shown (relative to west). Assume sprinter takes off perpendicular to block. Example 5 Determine the resultant acceleration of the sprinter. 20 o θ=?

Equilibrium Object is in equilibrium or is balanced when ΣF=0 in a particular direction. Determine the weight of the hanging picture.

A traveler pulls a suitcase of mass 8.00kg across a level surface by pulling on the handle with 20.0N at an angle of 50.0° relative to horizontal. Coefficient of kinetic friction against the suitcase is μ k = Determine the acceleration of the suitcase. Example2

Inclines y x Consider a block that slides down a frictionless incline. θ Since the surface of the incline does not lie along x or y, we can rotate our x-y axis to meet our needs. Draw the force vector, F g, on the box

y x Resolve the force of gravity into components θ FgFg θ

θ FgFg What is the normal force on the block equal to?

A skier moves down a ski slope angled at 30 o. If the length of the slope is 50m, determine the time it takes to reach the bottom if the skier starts from rest. Ignore friction. Example

A block of mass 2kg is projected up a rough incline (u k = 0.40) at 6.2m/s where the angle of the incline is 25 o. Example 2 a) Determine the distance along the incline it slides before coming to rest. b) Determine the acceleration of the block on the way down the incline.

System of Bodies: Multiple bodies connected together is called a system where all bodies MUST accelerate at the same value.

Assume m A = 1kg, m B = 3kg, m C = 4kg and the surface on which they sit to be smooth. If block C is pulled with a force F equal to 15N, determine: a) The acceleration of the system. b) The tension in each string between A & B and between B & C.

Example2 Block m 2 (5.0kg) sits on rough surface where u s = Determine the minimum value of m 1 to accelerate the system. Assume a frictionless & negligible mass pulley. If m 1 = 6.0kg, determine the tension in the string if u k = 0.30.

Example3 Assume a frictionless & negligible mass pulley. If the system is released from rest, determine the speed of the 5kg mass after it has fallen for 1.3s. b) Determine the tension in the string.

Example 3 If m 1 is 4kg and m 2 is 3kg, determine the tension in the string if u k = Assume m 1 falls. Angle is 30 o