# What is Acceleration: Definition and 1000 Discussions

In mechanics, acceleration is the rate of change of the velocity of an object with respect to time.
Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the orientation of the net force acting on that object. The magnitude of an object's acceleration, as described by Newton's Second Law, is the combined effect of two causes:

the net balance of all external forces acting onto that object — magnitude is directly proportional to this net resulting force;
that object's mass, depending on the materials out of which it is made — magnitude is inversely proportional to the object's mass.The SI unit for acceleration is metre per second squared (m⋅s−2,

m

s

2

{\displaystyle {\tfrac {\operatorname {m} }{\operatorname {s} ^{2}}}}
).
For example, when a vehicle starts from a standstill (zero velocity, in an inertial frame of reference) and travels in a straight line at increasing speeds, it is accelerating in the direction of travel. If the vehicle turns, an acceleration occurs toward the new direction and changes its motion vector. The acceleration of the vehicle in its current direction of motion is called a linear (or tangential during circular motions) acceleration, the reaction to which the passengers on board experience as a force pushing them back into their seats. When changing direction, the effecting acceleration is called radial (or orthogonal during circular motions) acceleration, the reaction to which the passengers experience as a centrifugal force. If the speed of the vehicle decreases, this is an acceleration in the opposite direction and mathematically a negative, sometimes called deceleration, and passengers experience the reaction to deceleration as an inertial force pushing them forward. Such negative accelerations are often achieved by retrorocket burning in spacecraft. Both acceleration and deceleration are treated the same, they are both changes in velocity. Each of these accelerations (tangential, radial, deceleration) is felt by passengers until their relative (differential) velocity are neutralized in reference to the vehicle.

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4. ### Electron in a time variable magnetic field

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7. ### Rise of Liquid from Horizontal Acceleration

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12. ### Question involving angular acceleration of a spinning wheel

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13. ### Rocket acceleration problem: confused about Newton's 2nd Law

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14. ### Acceleration & Normal Force of a Box: 4 m/s2 & 418 N

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15. ### I How does the mass of the wheels affect the car's acceleration?

Hi, I found this interesting thread, https://www.physicsforums.com/threads/accelerating-a-car-including-the-moment-of-inertia-of-the-wheels.930374/ but as it has been closed to replies, I decided to ask here. The thread ended up with the equation: where τ - 200Nm engine torque provided on...
16. ### Friction, Mass and Acceleration: Analyzing Block Motion

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17. ### B In uniform acceleration, mean velocity ##\bar v = \frac{v_0+v}{2}##?

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18. ### Angle of acceleration in non-uniform circular motion

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19. ### Points of inflection on acceleration graph

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20. ### Find the total time taken and acceleration in the given problem-Kinematics

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21. ### A or B? Increase in Velocity Backwards & Acceleration Forward

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22. ### Acceleration of Uranium 238 ion through a potential difference

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23. ### What exactly is wrong here? (F=ma when Force and acceleration are zero)

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24. ### Which statement is true? (Velocity and Acceleration of a Tennis Ball)

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25. ### Given a Constant Acceleration magnitude of g/4, Find the value of t

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26. ### Does the gravitational rate of acceleration increase within a planet?

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27. ### Engineering How do I know that the angular acceleration is the same for both wheels?

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29. ### B Very basic acceleration problem (from a video on The Physics Classroom website)

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30. ### Find acceleration of Moving incline with a block on it

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31. ### Finding acceleration from Velocity vs Position graph

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32. ### Acceleration of a suitcase in an accelerating train after getting pushed

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33. ### Motion with Time-Dependent Angular Acceleration

I am not understanding how to even start the question

36. ### Finding linear acceleration of a spool and cable

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37. ### Leaking cart being accelerated

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38. ### I About Direct Laser Acceleration

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39. ### Find the acceleration of the system (2 blocks sliding on a table)

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40. ### I Acceleration in an electron field

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41. ### Kinematics of movement subject to a variable acceleration

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42. ### I Vertical acceleration of the water bubbles in a kettle?

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43. ### Solving an Inertial Mystery: Angular Acceleration and Mud

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44. ### B Fundamental Problems With Exam Question: Moving Truck & Acceleration

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45. ### Acceleration required for ship to avoid crashing into another ship

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46. ### Integration of acceleration in polar coordinates

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47. ### Understanding how time derivative = acceleration

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48. ### Acceleration of a person jumping off of a bathroom scale

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49. ### B Acceleration -- How is the intermediate displacement speed derived?

I don't know if I wrote it correctly
50. ### B Can anyone tell me some formulas for acceleration?

我是一名高中生，对加速度的一些计算感到困惑，请与我分享一些信息 (translation by the Mentors via Google Translate): "I am a high school student and confused about some calculations of acceleration please share some information with me"