2.1 
Jump to Book CoverPrevious Page
Next Page

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
Acceleration
How do we describe changes in velocity? Almost nothing in nature moves at constant speed for very long. Even a car on cruise-control speeds up and slows down by small amounts to compensate for hills. How do we describe changes in velocity, such as going from rest to moving, or from moving to rest? The answer is the concept of acceleration. Acceleration is defined in equation (2.3) as the rate of change of velocity. Acceleration is a crucial concept in the physics of motion. Acceleration, not velocity, is the result of applied forces.
Acceleration calculator
(2.3) a= Δv Δt
a  = acceleration (m/s2)
Δv  = change in velocity (m/s)
Δt  = change in time (s)
Acceleration
definition
What does acceleration mean? Equation (2.3) describes how acceleration is the change in speed (Δv = vf − vi) divided by the change in time (Δt = tf − ti). For example, if a car starts at rest and is moving at 30 mph ten seconds later, the car's acceleration is 3 mph/s, or three miles per hour per second. The speedometer increases by three miles per hour each second for ten seconds. Acceleration is the rate at which speed changes. Show Acceleration of a car
What are the units of acceleration? The units of acceleration are units of speed divided by units of time. For a typical car a convenient unit would be miles per hour per second. A powerful sports car can accelerate from zero to 60 mph in 4 seconds. The change in speed is 60 mph. The change in time is 4 seconds. The acceleration is 15 mph per second.
What are m/s2? Acceleration will usually be expressed in SI units of m/s per second, or m/s2. (This is sometimes written as m/s/s.) One meter per second squared means velocity changes by one meter per second each second. Understanding acceleration
Positive and negative Acceleration can be positive or negative; “deceleration” is another word for negative acceleration. For example, an acceleration of +4 m/s2 adds 4 m/s of velocity each second. A car starting from rest would move at 4 m/s after one second, 8 m/s after two seconds, 12 m/s after three seconds and so on. A negative acceleration of −4 m/s2 subtracts 4 m/s every second. A car moving at +40 m/s would be moving at 36 m/s after one second, 32 m/s after two seconds, 28 m/s after three seconds, and so on.
Test your knowledge 1) When an object moving with positive velocity is slowing down, the acceleration that it experiences is ___________.
  1. Positive
  2. Negative
  3. Zero
  4. Infinite
Show
2) A man is driving his car north on the highway at a constant velocity of 50 mph for 100 s. What is the value of his acceleration?
  1. 0.5 m/h/s
  2. 5,000 m/h/s
  3. 0 m/h/s
  4. Not enough information
Show
Solved Problem 2.2: Acceleration of two cars
Two cars accelerate from rest to 29 m/s. The first car takes 10 seconds and the second car takes 4 seconds. What is the acceleration of each car?

Acceleration for two different cars
Answer: The first car accelerates at 2.9 m/s2 and the second car accelerates at 7.3 m/s2.

Previous Page Next Page57