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.
Consider a planet with a mass 5x that of the Earth a distance of 3AU away from a star with a mass 1.5x that of the sun.
-What is the acceleration of the planet due to gravity from the planet on the star?
-How does this answer compare with the acceleration we feel on the surface of the Earth...
Homework Statement
In Figure 4, the coefficient of kinetic friction between block 1 and the incline is 0.2. Determine the acceleration of the system, assuming a frictionless policy.
Figure: http://i.imgur.com/jbTo1Nnh.jpg
Homework Equations
Please see below.
The Attempt at a Solution
Could...
Homework Statement
You are an engineer in charge of designing a new generation of elevators for a prospective upgrade to the Empire State Building. Before the state legislature votes on funding for the project, they would like you to prepare a report on the benefits of upgrading the elevators...
Homework Statement
A car, length 2.4m, traveling at 26m/s wants to pass a large truck, length 12m, also traveling at 26m/s. If the car can accelerate at 4.4m/s2, how much time will it take the car to pass the truck (note the back of the car has to be in front of the truck)? How far will the car...
Hello,
I just did a practice physics problem that asked if an object with constant acceleration can change direction twice. The answer was no. What if you had an object attached to a string spinning at constant velocity. Is the tangential acceleration constant?
Homework Statement
When the hand is rotating about the wrist in the sagittal plane its centre of mass has an acceleration of 3m/s(squared) in a horizontal direction, its mass is 2kg and the vertical direction (i.e. Y) is against gravity. The hand travels through 30 degrees. If the distance from...
Homework Statement
A baby falls from the top of a ##45 m## building. What is the minimum speed that Spiderman must push off from the same building one second later in order to catch the baby before she strikes the ground?
Homework Equations
Please see below.
The Attempt at a Solution
I tried...
Homework Statement
find the accleration at t=3 seconds
Homework Equations
vf-vi/tf-ti
The Attempt at a Solution
velocity at 3sec is 2 m/s and at 0 sec is at 4m.s
time is 3-0
2-4/3-0, [/B]
Ive been looking at the simple physics problems for 2D motion. For example, a ball starts from rest and is thrown at 5m/s at an angle of 30 degrees with respect to the ground on earth. Most of the problems assume that the acceleration in the x-direction is 0. Doesnt there need to be an initial...
Homework Statement
a=1.8m/s/s
v/sf=7.6m/s
u/si=?
t=2.5s
Find the initial speed[/B]Homework Equations
a=v-u/t
The Attempt at a Solution
a=v-u/t
1.8=7.6-u/2.5
u=7.6+1.8/2.8
u=3.357...
u=3.36m/s
Is this correct? Sorry if the layout is messy this is my first time using it.
Maybe I've gotten them figured out, but I'm still very much a physics newbie and thus not feeling confident, so if anyone could please review my work, I'd greatly appreciate it!
1. Homework Statement
1) A car accelerates uniformly from 10 m/s to 20 m/s in 5 seconds.
a) How far does it travel...
"A dog running in an open field has components of velocity vx = 1.8 m/s and vy = -1.8 m/s at time t1 = 10.8 s . For the time interval from t1 = 10.8 s to t2 = 23.2 s , the average acceleration of the dog has magnitude 0.45 m/s2 and direction 32.0 ∘ measured from the +x−axis toward the +y−axis."...
Homework Statement
Hi, I have a quick question about an experiment I am doing.
I did an experiment where I rolled a ball over a flat surface and dropped a ball from a height, and I was asked if the ball rolling over the flat surface (1-d) motion is subject to constant velocity? I was also...
My question is simple, in the problem on the picture that i uploaded, why is -fk =ma
I understand the friction is in the negative direction, só it is negative, but the netforce, and the aceleration, are also in the negative direction ,só why are they positive? Shouldt it be -fk=-ma ?
Homework Statement
Homework EquationsThe Attempt at a Solution
I assume that the wheels are 8ft apart in both x and y direction.
Let's denote the length and width of the car by 2l = 8 ft.
The torque about an axis connected the contact points of rear wheels :
##\vec \tau = [\{l( \hat x +...
So the equation for angular acceleration on the AP physics sheet reads α = ΣT / I. I am required to prove that the units on each side are the same however I can't figure out how to get the rad/s^2 unit for angular acceleration into the same form as the right side which is N*m/ kgm^2
Any help...
Homework Statement
A hot air balloon is released from the ground & rises up with a constant acceleration of 4 m/s^2. When it is 16 meters above a sandbag is dropped.
What is the time taken for the sandbag to hit the ground?
Homework Equations
v^2=u^2+2as
v=u+atThe Attempt at a Solution...
Homework Statement
While strolling downtown on a Saturday afternoon you stumble across an old car show. As you are walking along an alley toward a main street, you glimpse a particularly stylish Alpha Romero pass by. Tall buildings on either side of the alley obscure your view, so you see the...
There's a common example to explain time dilation that states ...
"if you traveled at a speed close to the speed of light and came back in a round trip of 1 hour , you may find that on the departure frame of reference 2 hours had passed"
but that 2 hours trip can't be done without accelerating...
Homework Statement
A power plant operator on a bicycle is pedaling at uniform acceleration of "a", when his initial velocity "u" m/s. After 6.2s, and 9.3s, the bicycle had moved 23.5m & 39.7m respectively. Find the value of "u" & "a".
Homework Equations
s=ut+1/2at^2The Attempt at a Solution...
Homework Statement
A flywheel turns through 40 rev as it slows from an angular speed of 1.5 rad/s to a stop. (a) Assuming a constant angular acceleration, find the time for it to come to rest. (b) What is its angular acceleration? (c) How much time is required for it to complete the first 20 of...
Hello,
I'm working on a (private) Software Project and Part of that is finding a Way to Predict Projectile Positions. My thought's are explained from a Code View a little bit, but I tried to clarify everything so everyone could understand what's going on.
(It's my first time in this Forum, I...
Something about collisions has been bothering me.
Let's say I have 2 particles with equal mass: one is moving at velocity v towards the other particle. Kinetic energy and momentum is conserved during this collision. However, I have a question: what is the acceleration of the particles during the...
Homework Statement
A pulley hangs of mass, m, and radius, R, hangs from the ceiling. Two blocks of masses, m1 and m2 are connected by a massless, non-stretchable rope on the pulley (assume no slipping). What is the angular acceleration of the pulley and what is the ratio of the tension forces...
In the equation v=u+at, u=5 m/sec and a=0, then v=5 m/sec. That means the body is moving with a constant velocity of 5 m/sec. In a velocity-time graph, the equation produces a straight horizontal line. Some texts say the body is moving with zero acceleration and others say it is moving with...
Homework Statement
Homework EquationsThe Attempt at a Solution
[/B]
Initially the rod is in rotational equilibrium , so net torque about CM is zero .
From torque equation about CM , we get
Tension T in the left string = Force F (kx) in the spring
Doing a force balance gives us T+F=Mg...
Homework Statement
In this problem, the solution says that aB= -(aA/6). But from what I know, acceleration is positive whenever an object is speeding up in the positive direction or when an object is slowing down in the negative direction. According to the problem, car B is slowing down and...
Homework Statement
Note : In the above setup the string lengths are unequal and the left angle is 30° and right angle is 60° .Homework EquationsThe Attempt at a Solution
[/B]
Just after the string is cut , writing force eq. for rod in vertical direction .
##Mg - Tcos60° = Ma_y ## (1)...
Not sure if I'm doing this right would love input
Consider a box m=50kg which is being pulled on a rough, horizontal surface by a person using a rope . Assume that the person is applying a force of T=150N on the block , the rope makes an angle of 30 degrees with the horizontal and the...
Homework Statement
Attached.
Homework Equations
Tangenital acceleration=r*alpha
3. The Attempt at a Solution
I thought it was just simply r*alpha=2*20=40 (choice A), but the answer key says choice B. I'm not really sure where I could have went wrong or its possible that there is a mistake...
I want to determine the acceleration due to gravity at a place using a helical spring.
For this, I've first calculated the extension in length of the spring (##x##) for a particular load (##L##) on the pan. Then I've plotted a graph for ##L## vs ##x## for different values of L and corresponding...
Homework Statement
A thin uniform rod (of mass 10.0 Kg and length of 1.20 m) is attached to a friction-free pivot. Initially, the rod is balanced vertically above the pivot (position A in the figure attached). If the rod falls from rest, calculate
a. the angular acceleration at position B...
Homework Statement
Three lead spheres, of mass 10.0 kg each, are located at three corners of a square of ice length 45.0 cm, as shown. A bead is released at the forth corner. By considering the gravitational forces among the four objects only, determine the magnitude and direction of the...
A mass of 0.3 kg is suspended from a spring of stiffness 200 N m–1. If the mass is displaced by 10 mm from its equilibrium position and released, for the resulting vibration:Plot a graph of acceleration against displacement (x) (for values of x from x = –10 mm to x = +10 mm)
Hugely struggling...
Consider a body of mass m at rest,then if I apply force f1 on that then it accelerates and attains a velocity of v1.then I remove that force..now the body is in uniform motion.if I apply a force f2 which is less than f1, then body will be accelerated or retardated?I know if same f1 is applied...
Set up: Gas on one side of a divider and an infinite vacuum on the other.
Question: When you remove the divider, over time, does the gas increase in acceleration, does it peak and then decrease or does it remain the same as the gas enters the vacuum/ leaves the side opposite the vacuum?f
Thanks
Homework Statement
Homework EquationsThe Attempt at a Solution
A) [/B]
s = √[(x2) + (y2 ) ]= a√[2(1- cos (ωt) ) ]|t= Γ
The book says, s = aωΓ
What I can do is ,
For very small Γ i.e. ωΓ<<1 , cos (ωΓ) ≈ 1 - {(ωΓ)2}/2
Then , I get,
s = aωΓBut, in question it is not given that ωΓ<<1. So...
Hi all,
Since the gravitational acceleration varies depending on location, then how do you know if your scale is precisely calibrated? If I use a calibration weight (e.g. 100.000000 g) that was manufactured and tested around at equator where g=9.780 m/s^2, in my lab at the north pole where...
Homework Statement
Given Ax,Ay,Az . I need to find the Vx,Vy,Vz ... The Coordinate Frame is Vehicle Axis System .. I have actual Speed to compare once i get the Vx,Vy,Vz ... The vehicle starts from the rest i.e Speed is zero and Accelerations are sampled at 0.05 seconds///
This is not a...
Homework Statement
I am working on a project dealing with the velocity and acceleration of satellites based on their distance from Earth. I was recommended to include some calculus in this project. Originally I thought I could just take the derivative of the orbital speed equation to find...
1. Homework Statement
this is a pulley system,
each masses are moving with acceleration with a1,a2,a3..
question)
1) How can i calculate the ratio a1:a2:a3 ?
2) How can i calculate the T(tenstion)?
2. Homework Equations
a1,a2,a3: acceleration of each masses.
g=10m/s2
weight of all pulleys...
Homework Statement
A small spring with a force constant of 72 N/m is held vertically and then stretched 16 cm. A 1.6kg mass is attached to it and then released. Calculate the acceleration of the mass at the moment of release.
Homework Equations
F = ma, Ee = 1/2kx^2
The Attempt at a Solution...
In uniform circular motion, direction of particle is changing at every moment but its speed remains the same. If the magnitude of velocity or speed remains the same, change in magnitude of velocity is zero. Then how come radial acceleration can have a calculated value since acceleration = change...
Homework Statement
Two cars of 540 kg and 1400 kg collide head on while moving 80 km/h in opposite directions. After the collision, the automobiles remain locked together.
Find the velocity of the wreck, the kinetic energy of the two-automobile system before and after the collision, and find...
according to f=GMm/r^2 if force changes based on a distance between 2 objects, so during free fall object is constantly changing its distance, so does that mean the Earth is exerting a non-constant force on that object? if that was right, why's that object accelerate at a constant rate of...
Please ignore strikeout (not sure why post is doing that)
I just watched a video from Caltech (Video link at bottom of post)
It says:
Displacement = Distance Fallen in first second of time in [m] * Time2
so Time2 has no si unit as it is just a ratio right?
Instant or Average Velocity = 2 *...
I understand that time slows with increased velocity and gravity, but even after reading this (article http://math.ucr.edu/home/baez/physics/Relativity/SR/clock.html) I'm a little confused as to whether or not acceleration alone, as in independent of (i.e., in addition to) velocity slows time...
Homework Statement
I am investigating how much force (F) a person of a certain mass (m) would need to go down one of the world's tallest waterslides, "Killimanjaro" for an important maths project.
Waterslide height: 49 m
Maximum speed: 25.28 m/s
Homework Equations
I feel like I am not taking...