Falling Definition and 1000 Threads

Wald says (paraphrased) "Let us attempt to destroy a black hole and create a naked singularity. Kerr-Newman black holes satisfy the relation M^2\ge Q^2 + (J/M)^2, where M,Q,J are the mass, charge and angular momentum of the black hole (and G and c are taken to be 1). Let us start with a...

If a ball is thrown upwards, another straight out, and another downwards, which will reach the ground with the highest velocity? After thinking about this for a while my conclusion is that they all will have the same velocity since they all have the same initial gravitational potential energy...

Homework Statement A biologist working 80 meters high in the Amazon tree canopy drops her pliers used for crimping bands on animal legs. 1) Assuming the pliers hit nothing on the way to the ground, how fast will the pliers be moving when they reach the ground? 2) When the pliers...

Homework Statement A 4.7 kg block is placed on an incline with a 14° angle. Ignoring friction, what is the acceleration of the block? If the coefficient of kinetic friction is 0.25 (and has overcome static friction) what is the acceleration of the block? If the incline is 4.6m long, what is the...

Homework Statement While on planet X, an object is thrown vertically upward with an initial velocity of 5m/s. If this object returns to the point of release in 3s, what is the acceleration of a free falling object on this planet? Homework Equations a=vf-vi/t The Attempt at a...

A mass M is released from rest on a smooth plane inclined to the horizontal at 14 degrees. Find the time taken for the mass to travel 1m down the incline and the velocit attained at the end of that time. I had no trouble with the first part - measuring the velocity and time for the part where...

Homework Statement A 700 g block is released from rest at height h0 above a vertical spring with spring constant k = 445 N/m and negligible mass. The block sticks to the spring and momentarily stops after compressing the spring 20.5 cm. (a) How much work is done by the block on the...

Homework Statement Hi all. I've got a vertical rod on a surface with a fixed and frictionless pivot at bottom end. The rod of length L is released and begins to fall. The forces acting on the CM of the rod should be: - weight force: mg - centripetal (radial) force...

Homework Statement A limp rope with a mass of 2.4 kg and a length of 2.1 m is hung, initially at rest, on a frictionless peg that has a negligible radius (see figure). The short end has length y1 = 0.84 m. What is the vertical velocity of the rope just as the end slides off the peg...

Homework Statement A 69 kilogram person falls from a 35 meter tower head first to the ground Homework Equations What is the maximum velicoity he reaches before impact? The Attempt at a Solution

Homework Statement mass of steel ball = 40g = .04 kg h1 = 2.00 m h2 = 1.60 m A steel ball is dropped from height of 2.00 m onto horizontal steel slab, rebounds to height of 1.60m. Calculate impulse of ball during impact. Homework Equations impulse J = F*dt J = P2 - P1 I tried...

I have been out of school for a few years so my physics is rusty. I need help figuring something out for my job. I need to know how high I must drop an object so that it hits the ground with an impact of 1000g's. The object is a cylindar and weighs 2lbs. I have been confusing myself. I...

Can this be explained in terms of inelastic collisions? This is what I think: The collision is perfectly inelastic because the person and the net move together with the same velocity. This means that the initial kinetic energy of the system (and therefore the kinetic energy of the person) is...

A toy car runs off the edge of a table that is 1.325 m high. The car lands 0.425 m from the base of the table. How long did it take to hit the ground? How fast was the car going? My tutor even had trouble with this, without a speed this is no solvable, at least to me. Suggestions on...

Homework Statement http://img202.imageshack.us/img202/3459/phys.png Homework Equations \DeltaY=VoYt+1/2gt2 The Attempt at a Solution Rearranging the equation (using \DeltaY=h), I get \sqrt{}2h/g which, from what I understand, means it takes \sqrt{}2h/g seconds for the monkey to...

Homework Statement If a fish is attached to a vertical spring and slowly lowered to its equilibrium position, it is found to stretch the spring by an amount d. If the same fish is attached to the end of the unstretched spring and then allowed to fall from rest, through what maximum distance...

Homework Statement From the top of a tall building, a gun is fired. The bullet leaves the gun at a speed of 340 m/s, parallel to the ground. As the drawing shows, the bullet puts a hole in a window of another building and hits the wall that faces the window. (y = 0.48 m, and x = 6.0 m.) Using...

Homework Statement Stephanie hits a volleyball from a height of 0.8m and gives it an initial velocity of 7.5m/s straight up.? a. how high will the volleyball go? b. how long will it take the ball to reach its maximum height? (hint:@ max height, v= 0m/s) Homework Equations im not...

Homework Statement A parachuter of mass 75 kg falls towards the Earth at a speed of 25 ms-1. What is the resultant force acting on the person? a. 750 N b. 450 N c. 1,350 N d. No net force e. 1,500 N Homework Equations F = ma The Attempt at a Solution I think the answer is...

Homework Statement The question I'm working on says "A special, frictionless, thin meter stick is initially standing vertically on the floor. If the meter stick falls over, with what angular velocity will it hit the floor?" Homework Equations v_rot=rw, I=1/12mL^2, KE=1/2Iw^2 The...

So i was thinking, if you drop a ball that has a bouncy property to it, it will travel half as high after the bounce, then in theory it will bounce half as high, and half, and half, and half but never reaches zero this is not true in reality though, because there of a loss of energy due to...

Homework Statement A baseball is seen to pass upward by a window 28 m above the street with a vertical speed of 8 m/s. The ball was thrown from the street. (a) What was its initial speed? (b) What altitude does it reach? (c) How long after it was thrown did it pass the window? (d)...

I'm given the initial conditions vnot=0m/s, hnot=3000m, and tnot=0s After 35 seconds of freefall, the chute opens. I am to write a piece-wise define diff equation for the rate of change of velocity, with the two pieces t<35 and t >_35. I am not given a mass. Now, I understand how to...

Homework Statement A flowerpot falls past two meter tall window in ¼ of a second. From what height did the flowerpot fall? Homework Equations To calculate the velocity of the pot while this is passing the window: v = d/t To calculate the height: v^2= v0^2 = 2gh → h= (v^2 - v0^2) / 2g...

Hello, I have got an question. How can I calculate the velocity of an object which I'll drop from a height of 1 meters with a starting velocity of 0 m/s? I did some research myself and found out that I can calculate this with using the following formula: St = 0.5 * 9.81 * t^2 St =...

A freely falling object requires 1.10 s to travel the last 20.0 m before it hits the ground. From what height above the ground did it fall? (Ans. in m.) I am completely lost on modeling this problem. Please help me figure it out.

Homework Statement In the Niagara Falls hydroelectric generating plant, the energy of falling water is converted into electricity. The height of the falls is about 50 meters. Assuming that the energy conversion is highly efficient, approximately how much energy is obtained from one kilogram...

Homework Statement the effect of air resistance is to slow down a moving object. It can be shown that height of a falling object is given by the following Homework Equations y=y0-[t+(e^-bt - 1)/b]g/b a. show that for short times this reduces to the expected expression y=y0-1/2gt^2...

Homework Statement A crane is in the process of lifting a pallet of bricks to the upper floor of a building. Suddenly a brick slides and falls off the rising pallet. You clock the time it takes for the brick to hit the ground at 2.5 seconds. The crane has height marking and you see that...

Homework Statement A wrecking ball is hanging at rest from a crane when suddenly the cable breaks. The time it takes for the ball to fall halfway to the ground is 1.31sex. Find the time it takes for the ball to fall from rest all the way to the ground. I think the formula to use is...

The velocity of a diver just before hitting the water is -10.2m/s, where the minus sign indicated that her motion is directly downward. What is her displacement during the last 1.10sec of the dive? I tried to use dthe x=1/2(Vinitial + Vfinal)t=40.8 but it's wrong, what am i doing wrong??

If you stand motionless under an umbrella in a rainstorm where the drops fall vertically, you remain relatively dry. However, if you start running, the rain begins to hit your legs even if they remain under the umbrella. Why?Now I know the answer, it's because when you run horizontally, your...

Can somebody please show me how to solve this problem? A flowerpot falls off a windowsill and falls past the window below. You may ignore air resistance. It takes the pot 0.420 s to pass this window, which is 1.90 m high. How far is the top of the window below the windowsill from which the...

While I was looking up about free falling chain problem(the question about a chain falling on to a table), I wondered how it would be if the chain is knotted. What I'm thinking is that if the chain has a knot, would it make much difference? Two questions; 1) Once the knot hits the table...

This is a 2d problem. If I drop a ball with mass m from a height L over ground. How large is the interval that the ball can possibly be on if m = 1 g and L = 2m. Use the uncertainty principle \Deltax\Deltap ~h to determine the interval. Am I supposed to think of this as a classical...

Homework Statement Hi guys, I have a question on problem 4.11 in Kleppner and Kolenkow's mechanics book. A chain of mass M and length L is suspended vertically with its lowest end touching a scale. The chain is released and falls onto the scale. What is the reading of the scale when a length...

Homework Statement postively charged bead having a mass of .61g falls from rest in a vacuum from a height of 5.9 m in a uniform vertical electric field of magnitude 11600 N/C. The bead hits the ground at a speed of 19 m/s. acceleration of gravity is 9.8 m/s^2. find the charge on the bead...

Homework Statement A pen falls from the top of a roof. We know that it takes 1.5 seconds to fall the last 1/4 distance. Find the height of the roof from the ground. Homework Equations x=x_0 + v_0 * t + 1/2 gt^2 v=v_0 + gt The Attempt at a Solution Since the problem does not say...

Homework Statement An object with mass 10kg is dropped from a height of 200m. Given that the constant k in the equation is 2.5Nsm^-1 mv'(t) = −mg − kv(t) approximately how many seconds does the object hit the ground? Homework Equations v' + (k/m)v = -g The Attempt at...

This is my first post here so please bear with me if I'm doing something wrongHomework Statement A cargo plane is flying horizontally at an altitude of 10.1 km with a speed of 910 km/h when a large crate falls out of the rear loading ramp. (Ignore any effects due to air resistance.) How long...

I've been online searching for interesting stuff about maths and physics. I came across to this question in yahoo answers that i found quite interesting. The first equation would be working out how long it takes to reach the ground, and how fast it's going when it arrives. This is actually...

Homework Statement b) A person standing on the edge of a 100 m high cliff drops a 0.5 kg stone vertically downwards. Determine the final velocity of the stone after falling 100m, and its kinetic energy. Homework Equations Final velocity v = √(2gx) The Attempt at a Solution final...

A juggler performs in a room whose ceiling is 4.2 m above the leve of this hands. He throws a ball vertically upward so that it just reaches the ceiling. a. with what initial velocity does he throw the ball? b. what time is required for the ball to reach the ceiling. He throws a second ball...

Ok, so imagine observer A is moving along with a measuring rod of length L that is being slid along the ground by a rod that holds it steady by pushing it against the ground as it slides (no tilting whatsoever, the base of the rod remains firm against the ground), at a velocity comparable to c...

Homework Statement A bolt comes loose from the bottom of an elevator that is moving upward at a speed of 6.88 m/s. The bolt reaches the bottom of the elevator shaft in 3.90 s. How high up was the elevator when the bolt came loose? Homework Equations d= v(initial)t + .5at^2 The...

Homework Statement An object falls from height h from rest. If it travels .5h in the last second before hitting the ground, determine how long it takes to fall and the height h. xi = .5hm, t =1s, a = 9.8m/s^2, xf = 0m, Homework Equations Vf = Vi + at xf = xi + .5at^2 The Attempt at a...

The problem is: A snowball is dropped from the top of a building, evaporation causes the mass m of the snowball to decrease at a rate proportional to the snowball's speed as the snowball falls, so that M' = k * abs(y') where y denotes the vertical distance from the ground and k is a...

Hi this is my first post thanks to who ever contributes! Homework Statement A man drops a ball from the top of a 22m building. At the same instant his friend below throws a ball upwards at 22 m/s. What distance from the ground do the two balls meet. Ball A ------- v1 = 0 m/s a = 9.8m/s down...

If a apple falls on my head, what is the physical value that makes my head hurt?

Is a falling elevator a valid inertial frame? The title about says it. Is a body, (frame) free falling in a gravitational field a valid inertial frame as defined by SR? Thanks