Freefall Definition and 118 Threads

1. An arrow is shot vertically upward with an initial speed of 25 m/s. When it's exactly halfway to the top of its flight, a second arrow is launched vertically upward from the same spot. The second arrow reaches the first arrow just as the first arrow reaches its highest point. What is the...

Hey all, I was hoping to settle a debate once and for all. Suppose you've got two identical objects, in our hypothetical situation they were mini-vans. One of these is empty and the other is filled with something heavy like lead so that it is 100x the weight of the empty one. Both objects...

Acceleration (a or 9.8 for simplicity); initial velocity (vf); distance (d); Initial velocity (vi) trying to find a formula to answer "how far would you have to fall to reach x speed" where x is input from user. Is it possible to answer this using two steps, first find time then find...

Hi All, Assuming Stokes drag, wikipedia suggests this problem (the solution for v(t) ) has an analytical solution. Is this right? http://en.wikipedia.org/wiki/Drag_%28physics%29#Very_low_Reynolds_numbers.E2.80.94Stokes.27_drag Could someone point me to the derivation online? Or a...

A sphere inside an elevator is falling at terminal velocity. Say the elevator cables break and it starts to freefall, what happens to the sphere's velocity? I have developed some rudimentary solution but would like to see a confirmation.

Im new to these forums. Hope i posted this in the right section. I watched the movie "The a-team". There is a scene where there is tank under free fall, and they fire the canon sideways to move the tank whilst free fall. I wish to calculate if this is possible or if possible, how much exact...

Hi all, this is not actually homework or similar but the board seemed as the appropriate place for the question. I have an arm of 1m length pointing upwards from a rotation axis, on the end of the arm is a mass of 1kg, upon release the arm starts rotating downwards due to gravity (no other...

Homework Statement Ok, so I'm doing this science fair project on tennis ball bounce hieght, and I have to find the force that it hits the ground with. I'm trying to do this mathematically, because I can't record the time accurately in the actual experiment. The mass of the ball is 0.0567kg...

I worked two similar freefall problems with the same coordinate system, but had different signs for acceleration on each solution. I thought that if we say +y is up, then a = -9.8 m/s², so I'm confused as to why a = +9.8 m/s² for the second problem. Problem 1: Rock thrown from 30 m cliff with...

For a freely falling object dropped from rest, what is the acceleration at the following times? a.the end of the 2nd second b. the end of the 10th second c. the end of any elapsed time t Given- A= -9.80m/s^2 Vi=0m/s Do you have to find the final velocity, then acceleration?

(not a homework question, just something I thought about) http://img23.imageshack.us/img23/1130/hellhell.jpg So, if I'm told that the helicopter here let's go of an object and he wants the object to hit the truck. (all objects are "point mass"). Can I say right from the get go that, as...

Homework Statement Mass of the Moon is nearly less in 100 times than Earth's, and the diametr is less in 4 times. Find the acceleration of free falling at the Moon. Homework Equations F = G×((M×m)/R²) g = 9.8N The Attempt at a Solution M_moon = M_earth / 100 D_moon = D_earth / 4...

I'd like to start off by saying that all I want is explanations. My head forces me to think in a way that goes against what I "know" is right: Firstly: I "know" all objects fall at the same speed in a vacuum. What I understand from a vacuum is the absence of air, thus, absence of air friction...

Assuming a system with relatively small but non-negligable mass falling from infinity to a maximally massive black hole; Would there be a maximum possible coordinate velocity below c ? Is it possible to do an approximate calculation for this? A ballpark figure?? If there is a...

Homework Statement A man was standing on a cliff when he dropped a stone. One second later, he dropped another stone. How long before the distance between the two stone is 10 meters? (Show solutions with special attention to deriving the units.) Use g=10 m/s^2.Homework Equations Let d_1 =...

On planet X, an object weights 18.6N. Planet B, the magnitude of the free-fall acceleration is 1.42g (g=9.8m/s2) is the gravitational acceleration on earth) the object weights 29.8N acceleration of gravity is 9.8 m/s2. a) what is the mass (kg) of the object on planet X? b) what is the...

Homework Statement "an ex-physics student is exploring a cave and he comes to a deep abyss. since he has a stopwatch, he decides to determine how deep the abyss is. He remembers that sound travels at a constant velocity of 345 m/s he drops a rock and times how long it is until he hears it hit...

Homework Statement a mass drops from rest without air resistance, starting from coordinates x=xo, y=yo, z=0. compute its angular momentum about origin at time=t. compare it to the torque on the mass. repeat this, but pick your origin for the angular momentum and torque about the point...

Homework Statement Given a Height of release (d) and the Total time (T) form hand to floor. Derive general equations for vi, vf, h (in terms of d, T, and g) vi = velocity ball leaves hand vf = velocity of the ball the instant before it strikes the ground h = height of the ceilingknown height...

[b]1. Homework Statement A parachutist freefalls from a height of 4000 meters above the ground. Graph his distance vs. time as he falls stop your graph when his parachute opens 200 meters Homework Equations i tried a couple equations rate x time=distance (final velocity)= (initial...

How is it that airflow affects the freefall of a parachute? Obviously the larger the surface area of a parchute the slower the terminal velocity but how does the air interefere with a parachute or does it have no affect? :eek::confused::eek:

If one ball was thrown down with an initial velocity and another ball was thrown up with the same initial velocity. a) Which would have greater speed when it reaches the ground? b)Which has a greater displacement? c) Which ball will hit the ground first? d) Which traveled a greater distance...

This isn't really homework, but I'll be taking intro Physics in fall and am trying to get a grasp on the material ahead of time so I can do well. Homework Statement An alert hiker sees a boulder fall from the top of a distant cliff and notes that it takes 1.3s for the boulder to fall to...

Electric Motorbike Does 0 to 60 in Under One Second! http://gas2.org/2009/04/27/electric-motorbike-does-0-to-60-in-under-one-second/ "...All this gives the driver a G-force three times more than that faced by a skydiver during freefall!" Isn't that ... zero?

Homework Statement A baseball pitcher throws a ball vertically upward and catches it at the same level 4.2s later a) with what velocity did the pitcher throw the ball? Homework Equations The Attempt at a Solution I put this into givens t = 4.2 s displacement = 0 m if the...

hi i was wondering if this formula is legitimate. it finds velocity when there is no friction and no time involved. \sqrt{2\ G \Delta\ x_{y}} =V G is 9.8m/s thanks, eliot

I have been trying to calculate the time it takes for an object of negligible mass to free fall towards an object with a large mass, taking into account that the gravitational acceleration experienced by the small object increases as it moves closer to the big object. The first thing I tried...

Homework Statement You fire a squirt gun horizontally from an open window in a multistory building and make note of where the spray hits the ground. Then you walk up to a window 5.0 m higher and fire the squirt gun again, discovering that the water goes 1.5 times as far. Ignore air...

I can't get this problem right...could someone help me r?

I don't know how to do this problem. I feel like I need more information. A ball is thrown upward with an initial velocity of 20 m/s. 1. How long is the ball in the air? 2. How long after release is the ball 15 m above the release point?

Homework Statement A rock is thrown horizontally from a cliff with a speed of 15 m/s. It falls half of the heigh of the cliff in the last three seconds of its fall. What is the total fall time? Homework Equations The Kinematic Equations The Attempt at a Solution Well here's what I...

An object falls a distance h from rest. If it travels 0.42h in the last 1.00 s, find (a) the time and (b) the height of its fall. so I know a=-g and I believe I need to use v= v0 + at to some extent. I also believe that they are trying to say that in the last 1s of the fall it traveled...

We are doing a project on the terminal velocity of a badminton shuttlecock and also have to find the drag coefficientof it. The problem that i have is that we are doing this very low budget I.E. throwing the shuttlecock from a window and filming it, now if i am correct to find the Cd we need to...

This isn't a homework problem exactly - I'm attempting to teach myself introductory physics and there's a question that's bugging me. The kinematics equations that I've seen so far for falling bodies all assume that little g is a constant, i.e. the distance of the fall of the object from its...

The weight of the cart is 4 N. The weight of the hanging mass is 4 N. Friction of the cart on the track is a constant force of 2 N magnitude. The mass of the string, the mass of the pulley, and the friction of the pulley can be neglected. What is the magnitude of the acceleration of the cart...

Heres a question I am really stuck on... Homework Statement If Person A drops a shot put weighing 1.5 kg from a height of 60m, and at exactly the same time Person B throws down a 100g mass at a speed of 10 m/s from 70m up, at what time would the mass overtake the shot put? Homework...

I need help getting the base equations for a situation like this so I can complete all of the other problems on the page. Thanks ahead of time. Homework Statement A stone is thrown straight upward and it rises to a height of 20.0m. With what speed was it thrown? Homework Equations...

Need help on another freefall problem. :( Homework Statement A foul ball is hit approximately straight up into the air with a speed of 35 m/s. a) How high does it go (above the bat): Already figured this out, 62.5m. The initial velocity in this problem was 35 m/s. b) If it clears the...

This is due by 10:00 tonight, I have gotten all the problems right except for the last one which I cannot figure out. If anyone could help that would be nice. :) Thanks. Homework Statement A lit firecracker is shot straight up into the air at a speed of 54.00 m/s. How high is it above...

Homework Statement A lead ball is dropped into a lake from a diving board 5.0 m above the water. After entering into the water it sinks into the bottom with a constant velocity which it hit the water for 3 seconds. and hits the bottom of the lake. How deep is the late ? Homework Equations...

A ball is thrown vertically upward with an initial speed of 15 m/s. Then, 0.92 s later, a stone is thrown straight up ( from the same initial height as the ball) with an initial speed of 27 m/s. The acceleration of gravity is 9.8 m/s^2. How far above the release point will the ball and stone...

A ball is thrown vertically upward with an initial speed of 15 m/s. Then, 0.92 s later, a stone is thrown straight up ( from the same initial height as the ball) with an initial speed of 27 m/s. The acceleration of gravity is 9.8 m/s^2. How far above the release point will the ball and stone...

Homework Statement For some reason, I just can't seem to understand this question. I didn't think it would be this bad. Anyways, A Rocket fires from rest with an upward acceleartion of 30 m/s^s for 2 seconds. After this time the engine shuts off and the rocker freely falls back to the surface...

Homework Statement I need to explain the physics of a free fall drop tower ride, 250 feet high, car holds 35 people and I'm assuming you would need the mass of the car so help me out there. Also, It is not supposed to exceed 3 g's when braking. It would be awesome if someone could help me...

Alright, well I haven't taken physics yet, so I set out to try and figure this problem out on myself. And the problem was, how long does it take for a person to fall 4000 feet if their terminal velocity is 120? Here is my process of thought to get the answer... Please correct me when I'm...

Here is an extract from a textbook. "While jumping or diving or on a trampoline a person will experience apparent weightlessness for a very short time. They will be in 'free fall'. It is much easier in these conditions to move your arms and legs since the force of gravity does not need to be...

Homework Statement Consider three ball bearings, one with a mass of 8 g, one with a mass of 16 g and one with a mass of 32 g. a.) What heights should the three ball bearings be dropped from so that at impact all three ball bearings will have the same velocity? b.) What heights should the...

The question is basically: You are on top of a edge that is 32.5m high and you drop 1 ball, moments later you throw a 2nd ball at the initial speed of 11 m/s. Which ball has a greater increase in speed, or is the increase the same? and prove it with a calculation. I started out with the x=x0...

does anyone know the answer to this? If the mass of an object in free fall is doubled, its acceleration a. doubles b. increases by a factor of four c. stays the same d. is cut in half

A fish is able to jump vertically out of the water with a speed of 4.5 m/s. How much time does it take for the fish to pass a point 0.4 m above the water on the way down? Can someone please post how to do this? I know you need to solve for t by using the quad. equation but I have done it...