What is Constant acceleration: Definition and 340 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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  1. H

    How Do You Calculate Initial Velocity with Constant Acceleration?

    Homework Statement Hi, A car is moving with constant acceleration covers the distance 74.0m. between two points in time 8.00s. Its speed as it passes the second point is 15.3m/s. Homework Equations The equation I am trying to use, is x-x_0 = (v_ox + v_x / 2)t The...
  2. H

    Constant Acceleration Question

    If an 81.00kg projectile is fired STRAIGHT up, with no air resistance, under the effects of gravity, and it reaches an altitude of 175km (175,000 metres), what was it's initial speed (what speed was it fired upwards at)? I disregarded the objects mass and calculated 1,715,000 m/s...would these...
  3. G

    Constant Acceleration: Thought Experiment & Answers

    I have this "thought" experiment. Imagine a large rigid object, a thin disc (dime) with the ("heads") surface area of the earth, accelerating in the "heads" direction for many years such that individuals on the surface (of the "head" side) experience the normal sensation of "gravity". This...
  4. A

    Particles under constant acceleration

    Homework Statement Okay, wordy. Read through though, please :smile: The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows uniformly with an acceleration of -5.60 m/s^2 for 4.20s, making straight skid marks 62.4m long ending at the tree. At what...
  5. L

    A question about constant acceleration close to the speed of light

    If a spaceship was to accelerate forever, at a constant rate that allowed the pilot to feel 1g, would he still feel 1g when the spaceship was close to the speed of light? I know that it will never reach the speed of light so the acceleration must slow as the ship speeds up, so I assume that...
  6. R

    How Fast Must the First Ball Be Thrown to Land Simultaneously with the Second?

    Homework Statement A ball is thrown upward from the edge of a 20m building with velocity V. One second later a ball is dropped from the same building. With what velocity must the first ball be thrown so that both balls land at the same time. Homework Equations x(t)=x+vx+1/2(ax)^2...
  7. A

    Distance under constant acceleration

    A body starts from rest with an acceleration of 11m/s². What is it's velocity after 6 seconds. (I got 66 for that) and how far did it travel? What forumla do I have to use for this?
  8. S

    Constant acceleration and free fall

    Hey, I've been having some problems with finding out the rocket's maximum altitude and was wondering if anyone could help. The question information is: A 200kg weather rocket is loaded with 100 kg of fuel and fired straight up. It accelerates upward at 34.0 for 31.0 , then runs out of fuel...
  9. P

    Help with constant acceleration

    I've just started studying physics and I'm having difficulty with this problem. A jumbo jet must reach a speed of 360km/hr on the runway in order to take off.What is the smallest constant acceleration needed for the jet to take off from a 1.80km runway? I'd appreciate some help getting...
  10. N

    Constant Acceleration Plane Problem

    The takeoff speed of a jetliner is 360 km/h. If the jetliner is to take off from a 2100 m long runway, what must be the (constant) acceleration along the runway? Velocity of jetliner=(360 km/h)(1000 m/ 1 km)(1 h/3600 s)=100 m/s v^2=initial V^2+2a(x-initial x) (v^2-(initial V^2))/(x-intial...
  11. A

    Two dimensional motion with constant acceleration problem,

    Basketball player covers 2.80m horizontally in a jump. His center of mass moves through the space as following: his center of mass is at elevation 1.02m when he leaves the floor, it reaches a maximum height of 1.85 above the floor, and its at 0.900m when he touches down again...
  12. K

    Kinematics - Constant acceleration and friction

    Unsolvable? Kinematics - Constant deceleration and friction Here's the way the problem is laid out: A car travels at 52.4 km/hr on a flat highway. If the coefficient of kinetic friction is 0.151, what is the minimum distance needed for the car to stop? Given: Vi = 52.4 km/hr (calculated...
  13. H

    Kinematics (constant acceleration)

    I have three problems that have stumped me. I attempted to utilize the equations my teacher said we'd be using but I don't know where I went wrong or what each equation is specifically for (e.g. finding displacement in constant acceleration or whatnot). Am I using the equations correctly...
  14. R

    Constant Acceleration of a train

    The question is A Train pulls away froma station with a constant acceleration of .4m/s^2. A passenger arrives at the track 6.0s after the end of the train has passed the very same point. what is the slowest constant speed at which she can run and catch the train? I am rather confused on...
  15. P

    The least constant acceleration

    OK, here's the problem: A large plane needs to get to a speed of 360 km/h on it's runway in order to take off. The runway is 1.8 km long. What would be the least constant acceleration required to take off? Physics just started, I need shock paddles to get me going again Thanks
  16. U

    Equation of Kinematics for Constant Acceleration

    Well, my first post here and it happens to be in the homework section. =P I finally escaped AP Chemistry (and got a 4 on my AP test!), but because I chose to take the AP Physics course for the upcoming school year, I undoubtedly have summer work. The task seemed simple enough: the teacher handed...
  17. E

    Relativity - Constant Acceleration

    Hi, I'm working out of Hartle's book Gravity and had a question about Ch. 5 problem 7. The problem states that a particle has constant acceleration along the x-axis, that is, the acceleration when measured in it's instantaneous rest frame is always the same constant. They want me to get the...
  18. E

    Constant acceleration and brakes

    how would i do this problem... You are driving to the grocery store at 20 m/s. You are 110 m from an intersection when the traffic light turns red. Assume that your reaction time is 0.50 s and that your car brakes with constant acceleration. 1)How far are you from the intersection when you...
  19. E

    Question about constant acceleration

    how would i do this problem... You are driving to the grocery store at 20 m/s. You are 110 m from an intersection when the traffic light turns red. Assume that your reaction time is 0.50 s and that your car brakes with constant acceleration. 1)How far are you from the intersection when...
  20. G

    Dimensional Analysis of Constant Acceleration at 1 g

    Newton's universal formula for calculating Gravity: Fg = G Mm / r² which states that two objects attract each other with a force equal to the product of their masses divided by the square of their separation, times a constant of proportionality (G), where G = 6.6742(10) x 10^-11 makes it...
  21. G

    Constant Acceleration Equation - physicist please

    I need a proper Physicist to settle an argument (and a bet) between myself and a friend over the correct equation for calculating constant acceleration (from rest) from velocity over time. my friend insists that A = V*T and I say A = V*T² in plain english, my friend claims that at 1 g...
  22. T

    Cylinder pulled away with constant acceleration

    for a homogeneous cylinder is pulled away with constant acceleration a(o). then a = a(o) - angular acceleration * r what is this equation stand for??
  23. B

    Constant Acceleration of police car

    Hi, this one is probably easy, but I just can't wrap my head around it. You are arguing over a cell phone while trailing an unmarked police car by 25m; both your car and the police car are traveling 110km/h (about 31m/s). You take your eye off the road for 2.0s because of the argument. At...
  24. M

    Constant acceleration problem.

    hello. i am confused on what forumla in particular you use to figure the answer out? A certain elevator cab has a total run of 209 m and a maximum speed is 322 m/min, and it accelerates from rest and then back to rest at 1.16 m/s2. (a) How far does the cab move while accelerating to full...
  25. K

    More constant acceleration questions

    Because there's no solution, and my book rated this problem as one of the tougher ones compared to the others, I have no idea whether I did this right, but my gut feeling is that it's wrong because I solved it waaaay too quickly. Question: Suppose you adjust your garden hose nozzle for a...
  26. K

    Question: Solving the 10000-meter run time problem with constant acceleration

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  27. T

    Constant acceleration of velocity

    A falling stone takes 0.28s to travel past a window 2.2m tall. From what height above the top of the window did the stone fall? So we have time and dinstance, but not the acceleration, which confuses me terribly. Do I need to find velocity? Or do I need to look for the acceleration? SO...
  28. W

    Constant acceleration (rotation)

    Starting from rest, a disk rotates about its central axis with constant angular acceleration. In 5.0sec, it rotates 25rad. During that time, what are the magnitudes of A) angular acceleration, b)average angular velocity.
  29. P

    How Do You Calculate Penguin's Velocity on Frictionless Ice?

    A 3.7 kg penguin runs onto a huge sheet of frictionless Anarctic ice. At t=0 is is at x=0 and y=0 with an initial velocity of 0.41 m/s along the positive x-axis. It slides while being pushed by the wind with a force of 0.29 N directed along the positive y-axis. Calculate the magnitude of the...
  30. D

    If a problem doesnt have constant acceleration

    do any of the normal kinematic equations still hold?
  31. A

    AP Phyz: Constant Acceleration

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  32. N

    Quick question regarding speed & constant acceleration

    I'm doing homework from the first week of Physics 111 in the 2nd chapter (this is university calc-based physics by the way). I am a bit of a slow learner (dyslexic :frown: ), so take it easy on me. I know the answer to the first question, but I would like to understand it. Here is the problem...
  33. G

    Constant acceleration physics problem

    Ok I have a question for everyone. Please help! I was given a graph with the problem, but I am going to try to put it in words. In the X-axis there is seconds. In the Y-axis there is meters. From 8 sec - 12 sec the car traveled 64 meters. The distance before the 64 meters is not given. It...
  34. N

    Objects Moving with a Constant Velocity & Constant Acceleration

    Q. An object starts at time t = 0 with a velocity of v0 = + 21 m/s and undergoes a constant acceleration of a = -5 m/s^2. a) How far from its starting ( t = 0 ) is the object at time at which it comes to rest? Solution: Since, the object undergoes constant acc. constant acceleration...
  35. A

    Speed with constant acceleration

    Using a Newton equation for position and substituting (v-v0)/a for t you can get the following formula: v^2= v0^2+2a(x-x0) where v^2 is supposedly speed. I understood speed to be tha magnitude of velocity which is the sqrt of the sum of the squares of the components (i.e. sqrt(vx^2+vy^2+vz^2))...
  36. R

    1 object constant acceleration

    A car, moving along a straight stretch of highway,begins to accelerate at .0483 m/s^2. it takes teh car 35.9 to cover 1 km. how fast was teh car going when it first began to accelerate? answer in m/s
  37. G

    Rotation with constant acceleration

    A flywheel has mass 40 kg and diameter 75 cm is spinning at 500 rpm. During 30 sec the wheel slows down due to friction. The wheel makes 200 complete revolutions during the 30 sec. At what rate is the wheel spinning at the end of the 30 sec? Can somebody help with this problem please?
  38. D

    Constant velocity or at constant acceleration

    Are we more likely to be able to walk at constant velocity or at constant acceleration?
  39. U

    Gravitational forces and constant acceleration

    Why isn't it true that an object tends to move with a velocity that is proportional to the force on it? For example, when an object falls, there must be a gravitational force on it, and this gravataional force in the downward direction gets larger and larger as the object falls and gets closer...
  40. D

    Help with Constant Acceleration Lab

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