Chapter 2 Motion in One Dimension Dynamics Dynamics
- Slides: 35
Chapter 2 Motion in One Dimension
Dynamics • Dynamics: branch of physics describing the motion of an object and the relationship between that motion and other physics concepts • Kinematics is a part of dynamics. In kinematics we are interested in the description of motion, without the description of the cause of the motion • Any motion involves three concepts used to study objects in motion: 1) Displacement 2) Velocity 3) Acceleration
Linear motion In this chapter we will consider moving objects: • Along a straight line • With every portion of an object moving in the same direction and at the same rate (particle-like motion)
Types of physical quantities • In physics, quantities can be divided into such general categories as scalars, vectors, matrices, etc. • Scalars – physical quantities that can be described by their value (magnitude) only • Vectors – physical quantities that can be described by their value and direction
Distance, position, and displacement • Distance (scalar) a total length of the path traveled regardless of direction (SI unit: m) • In each instance we choose an origin – a reference point, convenient for further calculations • Position of an object (vector) is described by the shortest distance from the origin and direction relative to the origin • Displacement (vector) – a change from position xi to position xf
Velocity and speed • Average speed (scalar) - a ratio of distance traveled (over a time interval) to that time interval (SI unit: m/s) • Average velocity (vector) - a ratio of displacement (over a time interval) to that time interval • Instantaneous velocity (vector) – velocity at a given instant • Instantaneous speed (scalar) – a magnitude of an instantaneous velocity
Velocity and speed
Velocity and speed
Instantaneous velocity • The instantaneous velocity is the slope of the line tangent to the x vs. t curve • This would be the green line • The light blue lines show that as Δt gets smaller, they approach the green line
Acceleration • Average acceleration (vector) - a ratio of change of velocity (over a time interval) to that time interval (SI unit = (m/s)/s = m/s 2) • Instantaneous acceleration (vector) – a rate of change of velocity at a given instant
Acceleration • The blue line is the average acceleration • The slope (green line) of the velocity-time graph is the acceleration
Case of constant acceleration • Average and instantaneous accelerations are the same • Conventionally • Then
Case of constant acceleration • Average and instantaneous accelerations are the same • Conventionally • Then
Case of constant acceleration To help you solve problems Equations Missing variables
Case of constant acceleration
Case of constant acceleration
Graphical representation
Graphical representation
Graphical representation
Graphical representation
Graphical representation
Graphical representation
Graphical representation
Graphical representation
Graphical representation
Chapter 2 Problem 36 A car accelerates uniformly from rest to a speed of 40. 0 mi/h in 12. 0 s. Find (a) the distance the car travels during this time and (b) the constant acceleration of the car.
Case of free-fall acceleration • At sea level of Earth’s mid-latitudes all objects fall (in vacuum) with constant (downward) acceleration of a = - g ≈ - 9. 8 m/s 2 ≈ - 32 ft/s 2 • Conventionally, free fall is along a vertical (upward) y-axis
Chapter 2 Problem 45 A certain freely falling object requires 1. 50 s to travel the last 30. 0 m before it hits the ground. From what height above the ground did it fall?
Questions?
Answers to the even-numbered problems Chapter 2 Problem 4: 12. 2 mi/h
Answers to the even-numbered problems Chapter 2 Problem 8: (a) 2. 3 min (b) 64 mi
Answers to the even-numbered problems Chapter 2 Problem 16: (a) 41. 0 m/s, 41. 0 m/s (b) 17. 0 m/s, much less than the results of (b)
Answers to the even-numbered problems Chapter 2 Problem 20: 0. 75 m/s 2
Answers to the even-numbered problems Chapter 2 Problem 32: (a) 20. 0 s (b) No, the minimum distance to stop = 1. 00 km
Answers to the even-numbered problems Chapter 2 Problem 50: (a) 2. 3 s (b) - 33 m/s
- Chapter 2 motion in one dimension answer key
- Motion in one dimension quiz
- Tape chart science
- A common flea is recorded to have jumped
- Free fall motion in one dimension
- Motion in one dimension
- Describing motion kinematics in one dimension
- Describing motion kinematics in one dimension
- Vy=vyo-gt
- Mathematical techniques
- Chapter 4 forces in one dimension
- Chapter 4 forces in one dimension answer key
- Simple harmonic motion formula
- Chapter 2 section 1 describing motion answer key
- What is acceleration
- Section 1 describing motion answer key
- Vectors in two dimension
- To describe a position in more than one dimension
- Undefined terms and basic definitions worksheet answers
- Time dimension of the study
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