Fall Definition and 921 Threads

hello, consider a man falling from a roof with a heavy box in his hands. what should he do with the box?

I'm trying to understand the basics of gravity. Newtons law of universal gravitation gives us : F1 = F2 = G (m1m2)/r2 Now on Earth you can simply that down to F = mg where g = G (mearth/R2) But using f = mg, a heavier object say a tennis ball should fall faster than a cannon ball. But...

Homework Statement It's a two part question, but it basically says this: a bolt drops from an elevator 9.0 ft from the ground, at what time does it hit the ground? Homework Equations x = x0 + vx0t + 1/2ax(t^2) The Attempt at a Solution since it's a free fall question and...

Homework Statement A person jumps from the roof of a house 4.4 m high. When he strikes the ground below, he bends his knees so that his torso decelerates over an approximate distance of 0.70 m. The mass of his torso (excluding legs) is 40 kg. (a) Find his velocity just before his feet...

Homework Statement Daniel's weight is 800 Newtons. According to Newton's Third Law, if the Earth pulls on Daniel with a force of 800 Newtons, then Daniel pulls on Earth with a force of 800 Newtons in the opposite direction. Why then is Daniel able to trip and fall down to the ground...

Homework Statement A ball moving with constant speed 1.0 m/s on a horizontal table rolls off the edge of the table. The ball hits the floor 0.50 seconds after leaving the edge. Suppose you roll the same ball on the same table with constant speed 2.0 m/s. After leaving the edge of the table...

This isn't homework persay and has nothing to do with school, but since it's a hypothetical question for personal interest if it belongs in the homework section or anywhere else please let me know. I apologize if it's in the wrong place. Hello everyone I participate on an online role playing...

Homework Statement A bolt comes loose from the bottom of an elevator when it is at a height of 15 m above the bottom of the elevator shaft. If the elevator is originally moving upward at a speed of 7.5 m/sec, assuming that the elevator continues to ascend at a constant speed, how high above...

This question has bothered me for few weeks: Lets say I was at some height above a super massive planet that has no atmosphere (i.e. no air resistance. If I were to begin falling what would stop me from being accelerated by the gravitational field of this planet to the speed of light? Assume...

Homework Statement http://i214.photobucket.com/albums/cc4/twinkie34005/untitled-10.jpg http://i214.photobucket.com/albums/cc4/twinkie34005/untitled-11.jpg Free fall problems, help please Homework Equations V = vi + a*t = .9+9.8*3.2 = 32.26 m/s Y = vi*t + ½gt² = 53.056 m...

Homework Statement A very silly person, intent on catching pigeons on the roof of an apartment building, trips and falls a distance of 44.6 m. She lands on a metal garbage can, crushing it to a depth of 0.422 m and walks away without having been seriously hurt. What acceleration did she...

Homework Statement It is desired to have a pile driver strike a pile with a speed of 20 m/s. Assuming the driver to be in free fall, from how high above the pile should be released? Homework Equations Used v^(2) = V(o)^(2) + 2ax v=final velocity V(o) =initial velocity a=acceleration...

Homework Statement During launches, rockets often discard unneeded parts. A certain rocket starts from rest on the launch pad and accelerates upward at a steady 3.30 m/s^2. When it is 235 m above the launch pad, is discards a used fuel canister by simply disconnecting it. Once it is...

can someone please help me?? I thought I had the answer to this problem, but it doesn't match the book's answer. I can't figure out what I'm doing wrong. This is the problem: A rocket is launched straight up with constant acceleration. 4 seconds after liftoff, a bolt falls off the rocket and...

My college Physics class keeps on increasing my interest for physics, and I'm getting bored of the in class work so I've decided that I want to try to make a physics engine so that I can play around with physics and help myself learn more of it without being confined to just what my professor...

I've been racking my brain to figure this one out, I really don't understand it. If you fill a balloon with air from your lungs, just manually blow it up, it should be carbon dioxide, no? Density of Carbon Dioxide at Sea Level: 1.977 g/L Density of Air at Sea Level: 1.2 g/L So it's...

Homework Statement A student drops a ball from the top of a tall building; it takes 2.5 s for the ball to reach the ground. A.What was the ball’s speed just before hitting the ground? B.What is the height of the building? Homework Equations v=V(not) + at x=V(not)t + 1/2at(Squared)...

Homework Statement A mass m is dropped from a height H onto a hard, flat surface. When it collides with the surface, it rebounds with the same speed it had before the collision. However, there is a constant force of air resistance f acting on the mass as it undergoes this motion. Answer the...

Homework Statement Two students are on a balcony 23.5 m above the street. One student throws a ball, b1, vertically downward at 14.1 m/s. At the same instant, the other student throws a ball, b2, vertically upward at the same speed. The second ball just misses the balcony on the way down...

Hi I have a question I need help with. Im trying to find out how much forces that a pouch (balloon) creates on the inside walls when it hits the floor after a fall. A pouch (balloon) with one litre of water falls from 1 meter down to the floor. How much force must the "walls" stand...

A model rocket with a mass of 0.50 kg is fired vertically from the ground. Assume that it is streamlined enough that air resistance can be ignored. Suppose it ascends under the influence of a constant net force of 2.0 N acting in a vertical direction and travels for 6.0 s before its fuel is...

My mechanics book says that if a rock falls freely to Earth from a certain height than it will be deflected slightly to the east due to the Coriolis force. But I don't understand why. Consider the following Wikipedia picture: If we imagine that we're looking at the nothern hemisphere from...

Hello everyone, So there is only one month left between my glorious summer and the beginning of my fall semester, also the beginning of my intensive mathematics major. This fall I'm planning on taking a total of FIVE advanced math courses in the undergraduate school where I'm at. Besides from...

Hi, thought this might be an interesting an kind of fun idea, post your 2009 schedule if your a student currently taking classes, also if you have some questions to ask the physics forums peanut gallery we can put them all in one space. I'll start Classes Linear Algebra- Using professors own...

If a high diver plunges from 36m above the water, what is the length of the time interval during which the diver falls through the air? - assume that throughout their dive, the diver is falling vertically from rest with an acceleration of 10\ ms^{-2} I'm not sure how to answer this. I think I'm...

Alright, so, first of all, I created this problem myself. I made this to study, so I considered it as my homework. 1. How long will a crumpled ball of paper that is 3 inches in diameter take to fall 45 meters IN FREEFALL, knowing that the sheet of paper used to create the ball was 210mm x 297mm...

re: GE = minus GMm/R. It`s said that as R increases M increases to the third power and therefore falling outward is downhill but the increase in M is due to an increase in the vacuum energy which converts to a certain amount of mass. However, the mass of vacuum energy is very small. Could...

I am going back to school 6 years after high school. This summer I am taking English 101 and Calc 1. As you would imagine, my skills are rusty. Although summer semester is 7 weeks long, I am doing okay: not too great, but not too bad either. Right now, I am in process of refreshing my math...

I might sound like an idiot asking this question, but, how does a body have zero weight in free fall??

Hello all, I'm entering a graduate program in materials science and engineering in the fall, and I was wondering if anyone had any generic or specific advice (or heads up) about grad school based on your experiences. Thank you.

Homework Statement An object falls from height h from rest. If it travels .50h in the last 1.00 s, find (a) the time and (b) the height of its fall. Explain the physically unacceptable solution of the quadratic equation in t that you obtain. Homework Equations Pretty much any free...

When you fall off a building and then you hit the floor, what actually kills you? I mean what energy or mechanism is acting on your organs and bones and damages them? The sudden change of momentum your body went through? The Kinetic energy you had before the impact? Please try to explain...

Homework Statement A rocket is launched to travel vertically upward with a constant velocity of say...20 m/s.After travelling maybe 35 s the rocket develops snag and its fuel supply is cut off. the rocket then travels like a free body, the height achieved by the rocket will be...

1. An airplane flying horizontally encounters a low pressure and drops, and you feel lighter. If your apparent weight during that time is 60% of your true weight, what is the acceleration of fall of the plane? If the plane now climbs back with an acceleration equal and opposite to the...

I'm having a hard time trying to figure out if Linear Algebra or the Foundations of Higher Mathematics would be best to take for fall quarter. I briefly thought about just taking both, but I'm not sure if I could handle it. Originally I was thinking about take linear algebra, but a friend...

I understand that mass warps spacetime, and am well familiar with the bowling ball/rubber sheet analogy, but that to me is a depiction without explanation of the process. It doesn't explain for me what actually causes an object, Newton's apple for example, to accelerate toward another mass, in...

Hi, having a problem with this question. I thought it was as simple as the conservation of energy, but I guess there is something I'm missing. The program we're using isn't accepting my answer, even when I use two significant digits. Thanks for the help, Cohort Homework Statement From...

Why a spinning top won't fall to the ground? yes I know this question must have been asked before right? tried looking for it on here but I couldn't find it.

why doesn't the electron fall into the nucleus!? yes I know this question must have been asked before right? tried looking for it on here but I couldn't find it. the only answer I have gotten to this was just that particles are quantized... yes yes, fine... but WHY? for instance, why does an...

Homework Statement A uniform chain of length L lies on a smooth table with part of its length b initially hanging over the edge. Show that the time required for it to fall off the table when released from rest is given by t = √(L/g) arccosh (L/b) Homework Equations...

Homework Statement 1)A 3.0kg chair at rest is pulled across the floor by a 20N force.If the co-efficient of friction between the floor and chair is 0.25, calculate: a)the net force on the chair. answer=13N b)the displacement of the chair after 2.0sm answer=8.4m...

Hello I was just revising for my Quantum Mechanics A exam and was considering the 1D double well model of an H2+ molecule. As I understand it Psi2 is non zero between the wells and therefore there is some negative charge present to which the H+ nuclei are attracted resulting in a covalent...

Light does gravitate --- there is plenty of sound evidence for this, such as gravitational lensing in astronomy. Gravity makes space refract, it seems. What theoretical explanation can be offered for this observation? The equivalence principle is often used, but invoking a principle smacks...

Homework Statement A small first-aid kit is dropped by a rock climber who is descending steadily at 1.2 m/s. a) After 4.2 s, what is the velocity of the first-aid kit? Answer in units of m/s. Ok i know that the velocity after the 4.2 sec is -42.36 however the question asks how far is the...

Homework Statement Determine the value of 'g' Homework Equations AnythingThe Attempt at a Solution I only know of the pendulum method. Can someone please show me of other methods to calculate g without the use of fancy equipment such as a picoscope.

Homework Statement Need to solve the differential equation which models the velocity of a sky diver. Homework Equations dv/dt = -9.8 + 0.0045Av^2 where A is cross sectional area (assume 0.75m^2) v(0) = 0 The Attempt at a Solution ok the problem is to find v(t) as a function time. as...

Having trouble with the equation to solve the problem. A flowerpot falls from the ledge of an apartment building. A person in an apartment below, coincidentally in possession of a high-precision timing system, notices that it takes 0.20 seconds for the pot to fall past his 4.0 m high window...

Hey guys need help beginning to solve the following: A skydiver accidentally drops a camera out of the plane. The diver notices the mistake 3.0s later and dives out of the plane with a downward velocity of 10.0 m/s. The camera experiences free fall(9.8 m/s^2), but the sky diver accelerates...

Homework Statement An airplane releases a spacecraft , after 2 seconds the spacecraft s engine starts providing it with a horizontal velocity of 6m/s relative to the aircraft. What is the magnitude and direction of the velocity after 2 seconds? After 3? Assume the spacecraft is in...

Homework Statement I was given a problem to solve for the speed of a body falling under gravity [equation (1)] where g is acceleration due to gravity, which was easy enough.. but then i thought i would extend it to the case where g is non-constant, and so arrived at equation (2), (where where...