Acceleration Definition and 1000 Threads

A non-moving observer is looking at two different rockets in space. One rocket is moving at a steady velocity of 0.5c, and the other rocket is currently moving in 0.5c but has steadily accelerated from 0.3c and will continue accelerating until it gets to 0.7c. Assuming that there is no...

Homework Statement A 12.0-kg box is pushed along a horizontal surface by a 24-N force as illustrated in the diagram. The frictional force (kinetic) acting on the object is 6.0 N A) What is the acceleration of the object B) Calculate the value of the normal force acting on the object C) If the...

So I am having trouble with a problem.. and this has been a thorn in my side for quite some time now. I am working on a science fiction idea where I use the rate of expansion of the universe as the rate of acceleration of a spaceship. The rate of expansion is about 70 km/sec/megaparsec.. and I...

Homework Statement Two cars are 1.4 km apart and driving towards each other. One car starts from rest and accelerates uniformly at 1.2 m/s^2. The other car is driving at a constant speed of 18 m/s. When will the cars meet? Homework Equations d=vt d=ut + 1/2at^2 d=vt-1/2at^2 v^2 = u^2 + 2ad...

Homework Statement A thin, uniform, 18.5 kg post, 2.10 m long, is held vertically using a cable and is attached to a 5.00 kg mass and a pivot at its bottom end (as shown below). The string attached to the 5.00 kg mass passes over a massless, frictionless pulley and pulls perpendicular to the...

Homework Statement Two objects of 2.8kg and 4.2kg are connected by an inextensible cord. The object's at rest on a plane inclined 22°, determine the object's acceleration and tension in the cord if a 60N force is used to push the object downward. Homework Equations ΣFnet = ma the plane is...

Homework Statement Homework EquationsThe Attempt at a Solution it is known that ##a_0 ##is the proper acceleration ## a= \frac{a_0}{\gamma^3} ## hence integrating it gets ## v = \frac{a_0t}{\sqrt{1 + (\frac{a_0 t}{c})^2}} ## but this is in terms of t how to make it in terms of t'

Homework Statement d=Vi t + 1/2at^2 What do each of these mean? Show that this is true d=vt-Solve v=Vf+Vi/2 - Substitute Vf with Vf= Vi+at Homework Equations v= average speed Vi=initial speed Vf= final speed The Attempt at a Solution Vit: This represents the initial velocity at said time...

Homework Statement In lab, we put a glider on an airtrack and used a pulley to move the glider. The mass on the pulley was changed with each iteration. I have created a graph to find the mass of the glider, but I don't know what the y-intercept is supposed to mean. The graph I have is linear...

Hi all, I've been lurking around the forums for a while to get help with homework but I figured I'd finally make an account to get direct feedback. I'm having problems with this centripetal acceleration problem, Homework Statement "In an old-fashioned amusement park ride, passengers stand...

Homework Statement acceleratin as function of time ##a(t)= 2t+1## we know that v(0)=0 and s(0)=0 find v(t) find v(5) find s(t) find s(3) and I was thinking about also what happens when t is negative number, is it possible to find also v(-2)? what about s(-3)? Homework Equations integration...

Homework Statement Rigid body (ship) rotate and moves around 3 axis (x,y,z) around the center of gravity. The position is of the center of gravity is not known. What is known: At a point (A) the accereleration, velocity and position and rotational acceleration, velocity and position are known...

I have to be missing something very obvious in this. Homework Statement A car travels 80km/h on a level road in the positive direction of an x axis. Each tire has a diameter of 66 cm. Relative to a person riding in the car, what is the velocity of a) center, b)top, and c) bottom of the tire...

Homework Statement 13.53 The tension in the sting of the simple pendulum is 7.5N when θ=30deg. Calculate the angular velocity and angular acceleration of the string at this instant. Homework EquationsThe Attempt at a Solution Is this correct?

(context) I can remember reading about an atomic clock that could show time running slightly differently rates at different heights, due to the differences in gravitation. Is it realistic to think of it the other way round, ie gravity as an effect of miniscule time rate difference ? If an...

Homework Statement A bowling ball sits on the smooth floor of a subway car. If the car has a horizontal acceleration a, what is the acceleration of the ball? Assume that the ball rolls without slipping. Homework Equations torque = R x F = Iα aball= Rα Isphere = (2/5) MR2 The Attempt at a...

https://drive.google.com/file/d/0B0NXDy0RMDe7MXhMcjZBdkhoSDg/view?usp=sharing PIC: [https://drive.google.com/file/d/0B0NXDy0RMDe7MXhMcjZBdkhoSDg/view?usp=sharing] 1. A rotating disk is connected with two arms AD and DB which are rotating with the rate of 0.2 rad/s^2 and -0.3 rad/s^2...

Hello, I was working on a worksheet. It gave a graph that was velocity vs. time. I was asked to find the acceleration rate for the given (specific) time in seconds. My first question is if the line on the graph for example is from 1-3 seconds, in that 1-3 second range, is acceleration constant...

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...

Homework Statement A frictionless surface is inclined at an angle of 30.0° to the horizontal. A 270-g block on the ramp is attached to a 75.0-g block using a pulley, as shown in Figure 4-62. (a) Draw two free-body diagrams, one for the 270-g block and the other for the 75.0-g block. (b) Find...

1. Homework Statement Given x and y position ... find magnitude of both velocity and acceleration and their direction at t = 2 ? x = 4t y = 30 - 2.2t^2 would the velocity's magnitude be sqrt(8^2 + 8.8^2) ? Homework Equations v = sqrt(vy^2 + vx^2) The Attempt at a Solution vy = -8.8 vx= 8...

Homework Statement Homework Equations F= maThe Attempt at a Solution For 8, I think the parachute causes Al and Betty to stop accelerating, so they both have the same net force. (Answer A) F= ma F=m*0=0 F=3m*0=0 For 9, I feel like Al should experience more air resistance than Betty to make...

Homework Statement A train has a length of 118 m and starts from rest with a constant acceleration at time t = 0 s. At this instant, a car just reaches the end of the train. The car is moving with a constant velocity. At a time t = 14.0 s, the car just reaches the front of the train...

Homework Statement A person is standing on an elevator initially at rest at the first floor of a high building. The elevator then begins to ascend to the sixth floor, which is a known distance h above the starting point. A plot of the acceleration as a function of time is shown in the figure...

Homework Statement A person standing on a train platform notices that the first train car, which is approaching the station, had passed him in 4 seconds, and that the second train car passed him in 5 seconds. After this, the front of the train stopped at the distance of 75 meters from the...

Homework Statement Imagine a ball on a string that we swing vertically so that the hight changes. By conservation of energy the velocity of the ball must change right? Because at the highest point of the swing it will have maximum GPE but at the bottom, minimum right? Watching many videos has...

I was assuming that the proper time lapse between ##r=2M## and ##r=0## increases with increasing acceleration outwards. According to this paper https://arxiv.org/pdf/0705.1029v1.pdf Fig.2. it turns out however that the proper time to reach the singularity is longer with low acceleration but...

I’m trying to calculate the theoretical jerk and acceleration curve/distance/time for an elevator. I have the constant starting jerk set to 1m/s3, constant acceleration set to 1m/s2 and full speed set to 1m/s. Looking at Wikipedia about both, I can work out the figures about acceleration but I...

I have collected data on a car accelerating down a straight track. I graphed it Position vs Time. Then I found the tangent slope at 5 points along the curve and plotted them as velocity. But then I linearized the position vs Time graph (position vs Time^2.) However, the slope of the velocity vs...

Hello Forum, If a force is a function of position x only, like Hooks's spring force F=-kx, the acceleration is also only dependent on the position x, i.e. a(x). At every instant of time t, the object has a specific velocity v(t), position x(t) and acceleration a(t), which all depend on the time...

Hi! So someone came up to me with this question during physics and its been bothering me because I didn't know what to say to them and I didn't know if my understanding is correct or not. The question was something like: " A 72 kg car is traveling at v=63km an hour when it gets into a...

Homework Statement Masses M and m are connected to a system of strings and pulleys as shown in the diagram below. The strings are massless and inextensible, and the p ulleys are massless and frictionless. A: Find the accelerations for M and m (Hint: Think about these two questions: Do these two...

That is to say, how does time behave in a region of space where multiple gravitational fields cancel out their accelerating effects? I understand that time "slows down" in a gravitational field, but does this depend on the actual presence of the field, or instead the actual net acceleration...

Hello, I was referring to this thread: https://www.physicsforums.com/threads/accelerating-atwoods-machine-problem.44305/ to solve a problem on accelerating atwood machines in which, naturally, one attempts to find the acceleration of each of the individual masses. Although I now understand how...

Homework Statement 13.34 The curved portion of the cloverleaf highway interchange is defined by ##R^2=b^2sin2θ##, 0<=θ<=90deg. If a car travels along the curve at the constant speed v0, determine its acceleration at A Homework EquationsThe Attempt at a Solution [/B] Is this wrong?

Homework Statement At one instant a bicyclist is 20.5 m due south of a park's flagpole, going due east with a speed of 14.1 m/s. Then, 3.95 s later, the cyclist is 36.3 m due west of the flagpole, going due north with a speed of 18.3 m/s. For the cyclist in this 3.95 second interval, find each...

Homework Statement A car is moving with a constant velocity of 18 m/s for 5 seconds, if in the next 5 seconds it travels a distance of 40 m, what is its final velocity? Homework Equations Δx= vit+ 1/2 at^2 vf= vi+at vf^2 = vi^2 + 2a (Δx) The Attempt at a Solution So I tried doing it different...

Homework Statement The mine skip is being hauled to the surface over the curved track by the cable wound around the 38-in. drum, which turns at the constant clockwise speed of 96 rev/min. The shape of the track is designed so that y = x2/28, where x and y are in feet. Calculate the magnitude of...

In uniform curved motion , I can get the acceleration from the equation : A = v2/r , but in non uniform the velocity is changing , so will the certipetal acceleration also change ?

A nucleon that consists entirely of two or more protons, would be accelerated evenly, as each proton would see the same force (barring any collisions or other extraneous events.) Each should experience the same force of repulsion or attraction that is causing them to accelerate, so they should...

(Mentor note) This thread was moved from another forum, hence no homework template. How do you deduce initial acceleration just from B, L, M, and I? (Telsa, length, mass, and current)

1. Homework Statement It's an auto closing gate. Two parts of the gate are identical. I had given to find the time taken to close the gate. The distance to close point (P) of the gate from closed event of the gate is given as "a". Sorry for my bad English. What i need to know is how the two...

I'd like to ask about a hypothetical situation. A human, wearing a jetpack, for example, accelerates forward with 200,000 m/s^2 and therefore, experiencing extreme g-force of roughly 20,408 g. If there will be a hypothetical device that will be able to redirect the gravity force (g) to elswhere...

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...