# What is Accelaration: Definition and 135 Discussions

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

I got to the quadratic equation of the motion where: 4gt^(2) - g(delta t)t - g(delta t) = 0 and tried to solve for t. In this case, we would take the positive discriminate since we are dealing with the passing of time. t = ((sqrt(17) g(delta t)) + g (delta t)) / (8g) However, this is the...
2. ### A Exploring the Electric Field of a Moving Charged Spherical Shell

The electric field inside a charged spherical shell moving inertially is, per Gauss's law, zero. If the spherical shell is accelerated, the field inside is not zero anymore, but it gains a non-null component along the direction of the acceleration, as mentioned, for example, in this paper. The...
3. ### Relationship between accelerations of blocks 1 and 2

Assume that the lengths of various sections of the string at an instant are as shown. So we can say that ##l_1 + l_2+l_3= k## at an instant of time ##t##, where ##k## is a constant. Taking the second derivative of both sides w.r.t. ##t##, we get \frac {d^2{l_1}} {dt^2} +\frac {d^2{l_2}} {dt^2}...
4. ### A misconception I have about impulse formula interpretation

The misconception came up from the following problem: "A 0.50-kg cart (#1) is pulled with a 1.0-N force for 1 second; another 0.50 kg cart (#2) is pulled with a 2.0 N-force for 0.50 seconds. Which cart (#1 or #2) has the greatest acceleration? " I know the answer is the following (I looked it...
5. ### Finding the acceleration of the ball in contact with the ground during bouncing

the v before hitting the ground immediately=4.85m/s the v after hitting the ground immediately= 3.96m/s I considered the down positive, then v= u+at 3.96= 4.85+ (a*0.16) so a= -5.56m/s*s The answer is 55m/s*s The parts that I don't get are why it must be -3.96 and why that velocity becomes...
6. ### B Newton's second law of motion -- Why is it F=m*a and not F=m+a?

Why F=m*a i.e product or multiplication and not F=m+a? i.e addition or summation?
7. ### I Is acceleration a more absolute/fundamental quantity in the universe?

Was wondering if acceleration seems to be a more fundamental property/quantity in the universe as compared to velocity or distance because acceleration can be defined in more absolute terms in a frame depending on the forces acting inside that reference frame. Considering a very simple example...
8. ### B How is the acceleration proportional to the removed force?

Image above is the question. Below image depicts solution. if F1 is removed then the acceleration of that mass must be sum of accelerations of remaining forces. Right?? But answer says that acceleration of that mass is equal to acceleration of F1. I don't understand it. Can someone explain it??

10. ### Find the unknown mass on a inclined rope pulley system.

First I calculated the forces that were working against mass B. m(A)g sin 30 + μm(A)g cos 30 = 12.86 N The force working with mass B is m(B)g = 9.8m(B) I thought I could solve for B using F=ma where 12.86 N = (2kg+m(B))*(0.58), but of course, 12.86 N is just the force required to make the...
11. ### Movement of a Ball Bearing within a cavity inside a Projectile

Summary:: Question concerning the behavior of a ball bearing inside a projectile fired straight up or at an arc. Within a projectile is a 1-inch cylindrical cavity, inside of which is a steel ball bearing that can freely roll along the length of the cavity. When the projectile is fired...
12. ### Inertial Force in Fluid Mechanics

According to one explanation, the left hand acceleration terms of Navier Stokes equations are the called the inertial terms. If you were to balance forces on the fluid particle, they would have to be equal and opposite to the forces on the right hand side (pressure gradient, viscous, and body)...
13. ### Finding the Average Acceleration

Hello, so I am working on a projectile motion lab but I'm not sure what to do right now. Essentially, the lab consisted of my classmates and I using an air table to show that the vertical and horizontal components of projectile motion are independent. During one of our trials, we placed a puck...
14. ### Unraveling the Mystery of Mass and Acceleration

So, this may be a really stupid question, and I strongly feel as though I'm missing something here. How can it be that objects of different masses have the exact same acceleration when mass is in fact resistance to acceleration? And then, if in (a vaccum) I throw upwards M and m ( a bigger and a...
15. ### Kinetic energy as a function of time

I got acceleration by dividing force by m then replaced a by dv/dt and then integrated it to get velocity as a fxn of time and hence got kinetic energy but problem is my ans does not match with any option can someone please compare their ans
16. ### Matt & Hugh play with a Brick and derive Centripetal Acceleration

Matt and Hugh play with a tennis ball and a brick. Then they do some working out to derive the formula for the centripetal force (a = v^2/r) by differentiati...
17. ### What is the normal force in A and B?

A welded square frame consisting of four equal rods each with mass m and length 2l can move in the vertical plane by means of two small wheels in A and B that move without friction along a horizontal and vertical track, respectively. The disc is released from rest in a position where the sides...
18. ### Slope Problem

Im really stuck with this problem ! any help would be much appreciated
19. ### Einstein's Elevator: Gravity vs Acceleration

In Einstein's thought experiment (if I understand it correctly) a person in a sealed elevator in space accelerating at 9.807 m/s2 would not be able to tell the difference between that and the effect of gravity on Earth. Is there any sort of experiment the person in the elevator could do that...
20. ### Simple question about a moving elevator cab

Homework Statement Question from fundamental of physics, Halliday Resnick Walker In Figure below, a ##m=0.250## kg block of cheese lies on the floor of a ##M=900 kg## elevator cab that is being pulled upward by a cable through distance ##d1 =2.40 m## and then through distance ##d2 = 10.5 m##...
21. ### Relevant equations for an airplane landing

The problem I'm pasting the problem below mainly for the plot of y vs x. A possible way to think of it I suppose the important thing here is to find y(t) with the condition that -amax<ay<amax, and vy(L/vp)=0 My attempt I've modeled acceleration as a(t)=-kt and got an equation for y(t) as...
22. ### Setting two expressions equal to each other

Homework Statement Two cars are facing each other on a long straight airport runway. They are initially separated by a distance of 1 km. Car A begins to accelerate towards the other car at a uniform 0.5 ms^-2. Ten seconds later car B begins to move towards the other car with a uniform...
23. ### Acceleration in an inertial reference frame

Homework Statement 3. (a) If an object's acceleration is zero in one inertial reference frame then is its acceleration zero in all other inertial reference frames? (b) If an object's velocity is zero in one inertial reference frame then is its velocity zero in all other inertial reference...
24. ### Plot the position of the particle x=Acosbt

Homework Statement The position of a particle as a function of time is given by x=Acosbt, where A and b are constants. The first question asks to roughly plot the position of the particle over the time interval (0,7) seconds. The second asks what time the particle passes the origin, and what...
25. ### Solving Force and Motion: Pulling 25.0 kg Sled 25m

<< Mentor Note -- New poster has been reminded to use the Homework Help Template when posting schoolwork questions >> A 25.0 kg sled is pulled (assume frictionless) with a force of 15.0 N at an angle of 20 degrees above the horizontal. (a.) How long will it take to pull the sled 25m? (b.) How...
26. ### Does acceleration go to zero instantaneously?

Here's the scenario: If a force is accelerating an object at a constant rate, and force is removed, does the acceleration instantaneously go to zero? The problem i see with that is that on the graph, the acceleration line would be constant, horizontal, and then when the force is removed to...
27. ### How long will the ball and the spring be in contact?

https://physics.stackexchange.com/questions/407908/if-i-push-a-ball-on-a-string-till-this-is-completely-compressed-how-long-will-t. This is my complete question. I've been wondering on this topic for quite a while. I really can't visualize what happens at the border between the spring and the...
28. ### Reviewing Kinematics for AP Physics Exams: When to Subtract Gravity?

Hello, I'm reviewing kinematics for an upcoming AP physics exam, but I seem to have forgotten a crucial fact. In typical rocket problems (when the rocket blasts off with an initial acceleration for example 5 m/s^2), why don't we subtract 9.8 from 5m/s^2 when using a value for acceleration? When...
29. ### B Resultant Force of a skydiver

When a skydiver falls at terminal velocity, and opens his parachute, what will be the direction of the resultant force immediately after he opens his parachute? As far as I know is that the direction of acceleration will be upwards since his velocity is decreasing. I am a bit confused regarding...
30. ### Time derivative of gravity due to acceleration

Homework Statement We have the equation for gravity due to the acceleration a = -GM/r2, calculate velocity and position dependent on time and show that v/x = √2GM/r03⋅(r/r0-1) Homework Equations x(t = 0) = x0 and v(t = 0) = 0 The Attempt at a Solution v = -GM∫1/r2 dt v = dr/dt v2 = -GM∫1/r2...
31. ### Change in time due to accelerated light-clock

Homework Statement A light-clock (a photon traveling between two mirrors) has proper length l and moves longitudinally through an inertial frame with proper acceleration ##\alpha## (ignore any variation of a along the rod). By looking at the time it takes the photon to make one to-and-fro...
32. ### Translational + Angular Acceleration of Free Body (not fixed)

Imagine a long brick in outer space. You apply a force tangential to the center of mass. The brick accelerates in a transitional and angular fashion. There are no constraints or fixed axis. How would I calculate the translational and angular acceleration? I would like to run some simulations...
33. ### Acceleration of object with friction: Homework help

A 50 kg box rests on the floor. The coefficients of static and kinetic friction are 0.70 and 0.50, respectively. a.) What is the minimum force required to start the box sliding from rest? b.) After the box starts sliding, the person continues to maintain that force. What is the...
34. B

### Tangential acceleration, linear acceleration, and torque

What is the difference between tangential and linear acceleration of a circular object (let's say a ball)? Also, how does the torque contribute to linear acceleration?
35. ### Slope of Force vs Frequency^2 and Radius vs Period^2 Graphs

Homework Statement An experiment that involved swinging a mass in a circle was conducted. After graphing both sets of data, I obtained linear graphs of which I calculated the slopes for. I got a slope of 3.5 for the force vs frequency^2 graph and a slope of 0.73 for the radius vs period^2...
36. R

### Completely stumped on this one -- Kinematic Conceptual problem

Homework Statement You are at a stoplight when you see a car approaching from behind at constant velocity. To avoid getting rear-ended, you accelerate forward with constant acceleration. Assume that you have managed to start at the last possible instant to avoid getting hit, as determined by...
37. L

### Average acceleration vector

Question: A car is moving north at 100km/h. An hour later it is moving east at 100km/h. Its average acceleration during this hour is: a) A vector pointing northeast b) A vector pointing southeast c) A vector pointing southwest d) A vector pointing east e) Zero Attempt: I confidently chose a) A...
38. ### Change in direction of velocity

Homework Statement If my car was moving to the right then I changed direction of motion to down, and the speed is constant and =5m\s, how to calculate acceleration Homework Equations Δv=vf-vi The Attempt at a Solution Make vectors addtion and use pythagorean theorem formula, so change in v...
39. C

### B G-forces exposed during maximum perfomance Takeoff (Heli)

Hello Folks I'd like to know if anyone of you guys know how to calculate the gforces in a glider (in this case helicopter) during maximum performance acceleration? Tonight I had a very serious discousion with a relative of mine who doubt that it's possible to accelerate from 0 to 140 kts within...
40. A

### Velocity from Acceleration

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...
41. A

### Calculate Acceleration using relative distances

Homework Statement There are two cars traveling in a same direction. The Second car has a camera mounted on it and has ability to give relative X and Y (in meters) distance of first car with respect to it. Given the Speed of Second car , Calculate the Speed and Acceleration of first car. The...
42. ### Calculating distance from acceleration as function of speed

I'm trying to calculate the displacement d of a plane as it accelerates towards lift-off velocity. The acceleration is given by the function a = a0 - kv2 where a0 is the constant acceleration from the plane's engine and the term -kv2 is caused by air resistance. I can't seem to find a way to...
43. ### What is instantaneous acceleration?

How their can be instantaneous acceleration, its impossible to have change in velocity at a particular position(instant), we can have velcoity or speed at a particular point but how can we have change in velocity at a particular instant?
44. ### Difference between instantaneous velocity and acceleration

Hi, I'm just beginning to learn physics on my own. It seems that instantaneous velocity and acceleration are the same thing. Is it reasonable for me to be confused about the two? If acceleration = final velocity - initial velocity / change in time ... then how this any different from...
45. ### Calculate Tube Uncoiler Reel Acceleration | P-J

Hello, I'm making a tube uncoiler and I'm trying to find the acceleration of the tube at the reel (a3) can someone help me with this. kind regards, P-J
46. ### Rolling of a Disc: Find Acceleration with Friction

Homework Statement A cart with mass M has four wheels (idealized as uniform discs), each of radius r and mass m, arranged symmetrically with respect to the cart. Find the acceleration of the cart when a horizontal force F is applied on it. There is no slipping between the wheels and the...
47. ### Solve Satellite Velocity Homework: Find Moon's Velocity

Homework Statement On the surface of a distant planet, objects experience an acceleration due to gravity of 20 m/s2. The distance from the center of the planet to its surface is 8.0 * 106 m. Find the velocity of a moon that is circular orbit about the planet at a height of 300,000 m above the...
48. ### Yo-yo: Vertical acceleration

Homework Statement A yo-yo consists of two cylinders with radius ##R##, mass ##M## and height ##H## connected by a smaller cylinder of radius ##r##, mass ##m## and height ##h##. Determine the yo-yo's acceleration in ##z##-direction, using its moment of inertia. Homework Equations Moment of...
49. ### Jumping straight up while skateboarding downhill

Hi, I understand the mechanics of jumping straight up and landing on the same spot when inside of a moving bus traveling at a constant velocity but what happens when I jump straight up when skateboarding downhill? Do I land on the same spot on the skateboard, do I land further back relative to...
50. ### Desired Accelaration to Torque

Hello, I would like to know the basic eqns in a simple Powertrain model. Where i have the Desired accelaration and the other quantities to calculate the tractive force. But i need to calculate the torque to the wheels. can anyone help me ?