2.1 
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Videos:
Interactive Simulations   Position and displacement in one dimension    Displacement and position in two dimensions    Solve v=dx/dt for dt    Velocity, position, and time (basic version)    Velocity, position, and time (more advanced version)    Acceleration (basic version)    Acceleration (more advanced version)    Static equilibrium    Static equilibrium and the lever    Newton's second law (basic version)    Newton's second law (more advanced version)    Circular motion interactive simulation    Orbits of the planets and dwarf planets    Orbits simulation Interactive Calculators   Speed calculator    Velocity calculator    Acceleration calculator    Velocity in accelerated motion    Average velocity calculator    Hooke's law calculator    Torque calculator    Rotational equilibrium and torque    Newton's second law calculator    Momentum calculator    Angular velocity    Linear velocity and angular velocity    Centripetal acceleration    Centripetal force    Law of universal gravitation calculator
1 - Science of Physics
2 - Forces and Motion      Chapter 2 at a glance      2.1 - Motion      2.2 - Force, momentum, and Newton's laws      2.3 - Circular motion      2.4 - Solving harder physics problems      2.5 - Chapter review3 - Energy Transformations4 - Waves and Sound
5 - Electricity and Magnetism
6 - Light and Optics
7 - The Atom
8 - Linear Motion
9 - Vectors and Forces
10 - Forces
11 - Newton's Laws and Gravitation
12 - Circular Motion and Gravitation
13 - Torque and Static Equilibrium
14 - Momentum and Collisions
15 - Angular momentum
16 - Power and Machines
17 - Harmonic Motion
18 - Waves
19 - Sound
20 - Electricity
21 - Electric and Magnetic Fields
22 - Electromagnetism and Induction
23 - Light and Color
24 - Geometrical Optics
25 - Electromagnetic Radiation
26 - The Properties of Matter
27 - Thermodynamics and Heat Transfer
28 - The Atom
29 - The Quantum Theory
30 - TBD
31 - TBD
32 - TBD
33 - TBD
34 - TBD
35 - TBD
36 - TBD
37 - The atomic nucleus and radioactivity
38 - Nuclear reactions
39 - Relativity
40 - Particle physics and the standard model
41 - Electronics (semiconductors)
42 - Nuclear technology
43 - Lasers and photonics
44 - Metals, alloys and materials science
45 - Communications technology
46 - Buildings and structures
47 - Energy technology
48 - Biophysics
49 - Matter and Energy, Space and Time
50 - Energy Transformations
51 - Nanotechnology
52 - Website Videos
53 - ExtraStuff
55 - Modeling Motion, Friction, and Center of Mass
56 - Work and the Conservation of Energy
2B: Acceleration
What is the difference between acceleration and velocity?
Acceleration is one of the most slippery concepts in understanding motion. Acceleration describes the rate at which velocity changes. This is a different quantity from velocity itself, which is the rate at which position changes.

Part 1: Modeling accelerated motion
Doing the Investigation
In this interactive simulation, you will create a model for the motion of the ErgoBot by adjusting the values of the initial velocity and acceleration. The goal is to cause the ErgoBot's motion to pass through the target circles on the position vs. time graph.
How to use the interactive simulation
  1. The interactive model shows position and velocity versus time graphs. Red circles on the position versus time graph are “targets.” Your goal is to adjust initial velocity (v0) and acceleration (a) so the curve hits both targets.
  2. [Run] starts the simulation. [Stop] stops it without changing values. [Clear] resets all variables to zero. [Reset] resets all variables and sets new targets.
  3. Enter values in the white boxes. The top score of 100 is achieved by hitting the center of each target.
Assess Your Knowledge
  1. Describe the meaning of v0 and a.
  2. How would the ability to set the initial position (x0) effect the difficultly of getting a perfect score?
  3. Why can you not set a constant value for velocity v in the second equation?
  4. Do you think the solution to this problem is unique or are there many possible solutions? Support your answer with evidence.
  5. What acceleration will change an object's speed from 1 m/s to -1 m/s in 10 seconds?
  6. A certain aircraft must reach a minimum speed of 50 m/s to take off. The passengers can withstand an acceleration of 5 m/s2 without undue discomfort. What is the minimum runway length the plane needs to take off?
Going Further
    Estimate the deceleration of a baseball thrown by a pitcher to a catcher as it is caught.

Part 2: A multi-step model
Doing the Investigation
In this interactive simulation, you will create a model for the motion of the ErgoBot by adjusting the values of the initial velocity, initial position, and two periods of acceleration. The goal is to cause the ErgoBot's motion to pass through the target circles on the position vs. time graph.
  1. The second model allows you to change the acceleration five seconds into the motion, halfway through.
  2. In this model, unlike the first, you can set the starting position (x0) in addition to the initial velocity and acceleration.
  3. Try to hit the centers of the three red target circles for a perfect score of a100.
Assess Your Knowledge
  1. Why can you not set the position and velocity when the cart begins the second half of its motion?
  2. How would not being able to set the initial position, like in the first model, effect the difficulty of getting a perfect score?
  3. Do you think the solution to this problem is unique or are there many possible solutions? Support your answer with evidence.
  4. An electric car test requires the car to go from rest to 30 m/s in 20 seconds, then apply the brakes to stop in 5 seconds. Determine the required accelerations for both speeding up and slowing down.
  5. In the preceding example, what distance does the electric car travel?
Going Further
    If another student performed this investigation and gave you the data. How could you calculate the total distance traveled if only given...
    • The initial position, initial velocity, and the first and second accelerations?
    • The velocity vs. time graph?

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