Falling Definition and 1000 Threads

Homework Statement A particle falls in Earth's gravity. The force of air resistance is F = −αv v where v is the velocity, v is the speed, and α is a constant. (The direction of the force is opposite to the velocity, and the magnitude of the force is αv2.) If the terminal speed is 20.2 m/s...

an object, P is thrown vertically up and after 3s later another object ,Q is thrown up with the same initial speed of 20m/s and at the same position. find: a) the time, answer: [T][/P]= 3.54s, [T][/Q]= 0.54s [b]2. i use this formula v=u + at v=0 , u=20m/s a=9.8 ,t=? but my answer is...

I'm sure this will sound like quite a childish question, but Is it possible that there are high amounts of gravity throughout the whole universe (probably not the right wording), and that all celestial bodies are falling in "nothing" at the same rate of speed.

Homework Statement "A 0.15 kg apple falls from a branch 20 m above the ground. If it hits the ground with a speed of 17 m/s, what was the average friction force (due to air resistance) exerted on the apple?" Homework Equations At first, I thought I would use conservation of energy, PE = KE +...

[b]1. a free falling skydiver reaches a terminal velocity of 65m/s before opening his parachute.the parachute can provide a deceleration of 30m/[s[2]. a parchutist cannot hit the ground at a speed greater than 5m/s without risking injury. what is the minimum height at which the skydiver can open...

[b]1. stone p is releasedfrom a cliff of height 122.5m above the ground. after falling a distance of 19.6m, another stone Q is lauched straight downward.if given that p and Q reached the ground same time, find the initial velocity of Q( answer :26.1m/s i using s=ut +1/2a[t][2] to find out the...

Homework Statement 13. Water falls at the rate of 271 g/s from a height of 56.2 m into a 776g bucket on a scale (without splashing). If the bucket is originally empty, what does the scale read after 3.14 s? Answer: 2.50e+01 N Homework Equations Density, estimate 1kg/m^3 F = ma (a =...

I was walking down the hallway at work and saw a poster. Someone must have put it up outside their office. It said that falling asleep with the TV on reduces the bodies production of melatonin. So I looked it up and found an interesting article on Discovery.com...

Will a free falling rod rotate ? When we consider a bicycle is turning on a flat plane, we know that there is friction, which provide centripetal force on the bicycle. And we know that the bicycle is no longer perpendicular to the flat plane so as to reach equilibrium. What I want to ask why we...

Homework Statement Under some circumstances a falling body B of mass m encounters air resistance proportional to its instantaneous velocity v. Use Newton's second law to find the differential equation for the velocity of v of the body at time t. Recall that acceleration a = dv/dt. Assume in...

Let's say we have 2 objects. "A" is 100 meters above the ground. "B" is one meter above the ground. Release object A. When A reaches B, B is released and falls too. Question... Do they hit the ground at the same time? Or does A get there first? Air resistance is not an issue... just the...

Ok I will come straight to point. I am almost done with my 2nd year in Electrical and Electronics Engg. (just a couple of weeks more to go...) And I am damm disappointed with myself. I am studying in MAIT, IP, Delhi, India. And I am really disappointed with the way we are doing engineering...

Homework Statement Two spheres of mass m are connected by a massless rod or length L, and set leaning against a frictionless wall so that the rod is perpendicular to the floor (also frictionless). The bottom mass begins to slide perpendicularly away from the wall, so that the top mass falls...

A body of mass m (kg) is falling vertically under gravity g m/s2 in a medium whose resistance to the speed of the body, v m/s, is proportional to vn (n positive). If the body was released from rest and has terminal velocity, vt m/s, use Newton's 2nd law of motion to show that its...

1. An elevator is moving upward with constant velocity V. We consider a frame of reference fixed to the elevator. Since it is not accelerating, our system is equivalent to, say, a frame of reference fixed to the ground (there are no inertial forces). Now, we are inside the elevator and let an...

Homework Statement I am figuring out the physics of the scene in the movie Get Him to the Greek where an actor falls into a pool but breaks his arm by hitting it on the concrete edge. Mass of actor = 73 kg Mass of arm = 4.75 kg Force to break an arm = 73 N Duration of fall = 3.0 s Homework...

What keeps the electron from falling into the nucleus?

http://www.physorg.com/news/2011-05-cern-scientists-confine-antihydrogen-atoms.html When I read this I couldn't get my head around it, they are try to suggest that something with mass would be repulsed by gravity instead of attracted by it. This would mean the antihydrogen has a mass of a...

Hello, Can anyone help me with that? It's a problem taken from Wald book on General Relativity,in the section of Schwarzschild solution Thanks Show that any particle (not necessarily in geodesic motion) in region II (r < 2M ) of the extended Schwarzschild spacetime, Figure 6.9, must...

I have here a quote from Hartle's Gravity, page 321: "The fraction of rest energy that can be released in making a transition from an unbound orbit far from an extremal black hole to the most bound innermost stable circular orbit is (1-1/\sqrt{3})\approx 42\%". My question is about...

Homework Statement A ball falls from rest through a viscous fluid in a tall beaker of height H. It reaches terminal velocity at height H/2. Draw the energy-time graph for kinetic energy and gravitational potential energy on the same axes. Homework Equations F=6πηrv The Attempt at a...

A dripping water faucet steadily releases drops 1.0 s apart. As these drops fall, will the distance between them increase, decrease, or remain the same?

I have been reading about black holes and am intrigued by the fact that when you use schwarzschild coordinates to describe a particle free falling radially into a black hole, it takes an infinite amount of coordinate time for the particle to reach the event horizon. Since the coordinate time in...

I'm working on a project where I'm trying to find the differential equation of a falling raindrop. The drop I'm considering will be under 10mm to eliminate the drops breaking apart and I've found that for that size, the drops will be spherical and traveling 6-8m/s. I've determined my air...

So I asked my teacher what would happen if I fell into a black hole and then shined a light back towards the event horizon. And he said the light would go away from me at c, but also go towards the center of the black hole. OK I understand this would happen if i was in free fall towards the...

Homework Statement Say I've got a rocket payload (there's no thrust, it's just dead weight) falling to Earth from an altitude of 260km and I want to calculate the time it takes it to fall to 160km. It's far enough away from Earth that I can't make the assumption that gravity is constant (it...

Okay, I run an Emergency Services and Rescue Unit and was asked a very interesting question regarding our Roof Top Safety gear. A question I couldn't answer last night and I am desperate to find the correct answer. The question posed was as follows: How heavy would I weigh if I fell from...

1.Homework Statement A giant yo-yo of mass 410 kg measuring about 1.2 m in radius was dropped from a platform 63 m high. One end of the string was tied to the platform, so the yo-yo unwinds as it descended. Assuming that the axle of the yo-yo has a radius of 0.3 m, find the velocity of...

Homework Statement R = 49 m theta = 29° Homework Equations Kinematic equations for Rotational Forces and Circular motion Kinetic Energy = 1/2*I*w^2 The Attempt at a Solution First I can find the moment of Inertia for a rod, which is: 1/12 * MR^2 However I need to use the...

Homework Statement Hi all :biggrin: The Attempt at a Solution First of all, can someone tell me how to get the eqn in hint? :redface: And when i try solving it using the hint ... of ball (velocity of separation) = e(velocity of approach) v' = e √(2gh) = √(gh/2) let the...

When an object free falls, its accerleration is constant, but does its speed change? If so is it practicing uniform or non uniform motion?

What is the difference between these two equations. m dv/dt = mg - kv and m dv/dt = mg - kv^2 as the equation modeling a falling body with air resistance?

Trying to figure how fast you would be falling after 268 feet? not worrying about resistance and in terms of weight just and average person... this is what I did.. is it correct? or way off vf^2 = vi^2 + 2*a*d vf^2 = 0 + 2* 9.81 * 90 vf^2 = 1765.8m^2/s^2 take square root vf = 42 m/s...

Could anyone please tell me how the acceleration of an object in a fluid varies with its velocity.

Hi I'm having trouble with my injury mechanics problem where a rigid window with frame falls from a verticle position on a person sitting below. Homework Statement The decorative wood-framed window below has been inadvertently left unrestrained in a nominally stable vertical position...

When the snow started falling, the boys noticed that the air in the night and snow had the same temperature. However, snow seemed to be cooler on touch... State the reasons in detail, why it is like that. Hello..Can someone help me with that ? It isn't homework..

Hi, If a particle falls radially into a Reissner-Nordstrom BH with Q<M (i.e the case where you have an inner and and out horizon), then where in the conformal diagram does the test particle cross the inner horizon r_{-}? See for example the righthand Penrose diagram of...

Homework Statement A physics student launches a model rocket from the ground at t=0. The rocket ascends with a constant vertical acceleration of a1= 2.5m/s^2 until T1= 5.0s, when the acceleration increases to a2= 5.0m/s^2 until T2= 10.0s. When t>T2, the engine shuts down entirely. (b) What is...

Can anybody help me with this question... according to classical mechanics what determines the magnitude of the acceleration of an object falling to Earth ignoring air resistance? i'm not sure if this is a trick question but isn't it just gravity and the mass of the object?

I've heard that In vacuum space, both lighter and heavier objects fall to the ground at the same but what stops the heavier object from falling down more faster than lighter object?

Homework Statement A 0.222 kg shoe is dropped onto a vertically oriented spring with a spring constant of 101 N/m. The shoe becomes attached to the spring upon contact, and the spring is compressed 0.110 m before coming momentarily to rest. What work is performed by the weight of the shoe...

Homework Statement A uniform chain of total mass m is laid out straight on a frictionless table and held stationary so that one-quarter of its length, L = 2.87 m, is hanging vertically over the edge of the table. The chain is then released. Determine the speed of the chain at the instant when...

I'm attempting to find the velocity of a sphere falling through a liquid with an upward countercurrent flow. I already have the velocity as a function of time in a stagnant flow regime, but do not have one with countercurrent flow. Here is the equation without countercurrent flow: v(t) =...

Homework Statement A object A falling down at terminal velocity of 20 m/s, at 1000m above the ground another object B fly at it at an initial velocity of 125 m/s. a) how much time before object A hits object B? Homework Equations X = Xo + Vo(t) + 1/2AT^2 G = 9.8 m/s^2 The...

This is for a mechanics class. I'm sort of re-learning how to apply calculus and differential equations in this class, so I get stuck trying to figure out how to apply the math I learned 2 or more semesters ago. Any help would be greatly appreciated. Thanks, m.g. Homework Statement...

Why is dark matter distributed in a web rather than falling into clumps ? Under the action of gravity normal matter falls into galaxies, stars, planets etc. How is it that DM doesn't do the same but instead is in web form ?

As I understand it, time (as seen by a distant observer) near event horizon of BH slows to "zero". It makes me wonder how long (as seen by a distant observer) it takes for matter to fall to the event horizon. I would guess this would be calculated via some appropriate integral (I am not...

I've been thinking about this for a model I'm devising. Assuming that you have an object of mass m, height h, coefficient of friction u, how large can you make the angle between the ground and the inclined plane. Otherwise, at what angle does the torque from the center of mass of the object...

Okay, I have seen the calculation for how long it takes to fall through the Earth if you had an evacuated hole all the way through it from pole to pole. The problem is that they always assume a constant density for the Earth, and in reality it is far from that. In fact I just watched a YouTube...

Hey I am having a bit of trouble finding the proper equation to use when solving a problem such as this... A physics book slides off a horizontal tabletop with a speed of 1.10 m/s. It strikes the floor at 0.350 s. Ignore air resistance. Find (a) the height of the tabletop above the floor, (b)...