Falling Definition and 1000 Threads

Homework Statement A rock is dropped from a sea cliff and the sound of it striking the ocean is heard 3.2s later. If the speed of sound is 340m/s, how high is the cliff? V0= 0 A=-9.8m/s2 Ttotal=3.2s Tsound=Y/340 Y0=Height Y=0 (height at sea) Homework Equations Y=Y0+V0T+1/2(-9.8m/s2)T2...

When a body falls from a height (h) under gravity,the work involved is mgh. How do you describe this work? Is it 'work done by the force (gravity) on the body' or 'work done by the body'. The confusion is, if work is done on the body the body gains energy; but if work is done by the body the...

Homework Statement A satellite in a circular orbit around the Earth with a radius 1.021 times the mean radius of the Earth is hit by an incoming meteorite. A large fragment (m = 65 kg) is ejected in the backwards direction so that it is stationary with respect to the Earth and falls directly...

A rocket shoots upward with a velocity of 500 feet/sec. Neglecting air resistance, how high will it travel? Is that even enough info to solve the problem? I don't remember how to solve that.

Einstein's equivalence principle states that free-falling observers are in local inertial frame, so one can construct a local Minkowski frame everywhere. So my question is whether the logic can be inversed, does every local Minkowski space represent free-falling? because in vierbein...

If an average adult male fell from a bridge (ex. golden gate) what would be the impact on his body when he hit still water versus water with waves. What is his acceleration, momentum, and his change of momentum when he hits the water With these in mind how does the fall affect his organs...

Homework Statement A trebuchet misfires and its 450kg projectile falls from the sling at the vertical height of the firing arm, 1) What force will the projectile hit the ground? 2) If the trebuchet is 5.40m tall with the firing arm in the vertical position, how long will the projectile...

Hi, in this thread I want to discuss some problem that I wonder. I'm interested in "Probablilty" The first wondering is How can I express that probability follow an exponential. I'm wonder why probability expess in exponential? and Can I show it, if I experiment something, that graph...

Homework Statement Two spheres of mass M1 and M2 are arranged one above the other as shown. They are separated by a fraction of a mm. They are released from rest and allowed to fall to the ground, a distance h = 6.5 m below. Mass M2 collides elastically with the ground and then elastically...

Homework Statement Well this problem consists in, as the title says. A rock fall down a well, and it took you 4 seconds to ear the noise. It would be a rather easy problem, if it didn't had the sound in consideration. Oh and rigth now I apoligize for any errors or mistakes, I'm portuguese so...

Homework Statement uploaded Homework Equations rocket equation The Attempt at a Solution i can calculate the force acting on the chain by the ground using rocket equation but i cannot show that the velocity is that.

Homework Statement While exploring the canopy of the rainforest in equatorial South America, Anastasia falls from a branch 50.0 meters high. Exactly 1.1 seconds later Joe falls from the same branch. How high above the ground is Joe when Anastasia splats into the mud below?Homework Equations...

MAJOR EDIT: I fixed my position integral and got the answer to 1.ii) Homework Statement A parachutist jumps from a helicopter that's not moving. The mass of the person is 80kg, the quadratic drag is f = -Cv^2 where C = 3,52. Neglect the Earth's rotation effect. The parachute is opened as soon...

Homework Statement Does a falling object posses weight? Homework Equations F=mg The Attempt at a Solution I thought yes because it still has a mass and is accelerating due to gravity. However, the answer is No. If anyone could shed some light on this I would greatly appreciate it.

I'm dropping a sphere from a known height, and it enters a viscous fluid. I know the initial velocity as it enters the fluid, from there I need the velocity as it falls through the fluid (as a function of time). I know it should approach it's settling velocity (terminal velocity) and from...

Homework Statement [PLAIN]http://rawrspace.com/physics.GIF Homework Equations v=v0+at x=x0+v0t+(1/2)at2 W=\DeltaK=K2-K1 The Attempt at a Solution For the first part of this problem I attempted it this way which I think is completely wrong. I rearranged the first two equations...

Homework Statement A falling flowerpot takes 0.2s to fall past a window that is 1.9m tall. From what height above the top of the window was the flower pot dropped? g = -9.8 m/s^2, v1 = 0 m/s Homework Equations d = v1t + 1/2at^2 a = (v2 - v1) / t d = (v2 + v1) / 2 * t The Attempt...

It's an object that's falling from rest. The equation takes into account linear friction. in any case, this is is my code or program of whatever it is called: m=80;%Mass of ignorance g=9.8;%Gravity beta=1.6*10^-4;%Given coefficient for air at STP D=.4;%Diameter of Palin, assuming she's a...

so I am kind of stumped on this one here... A rock is dropped from a sea cliff and the sound of it striking the ocrean is heard 3.4 seconds later. If the speed of sound is 340m/s, how high is the cliff? - now i got some variables, v1=0 m/s time(total)=3.4s...

Homework Statement A clown stands at the side of a swimming pool. In his hand is a bag containing n red balls and n blue balls. At each step he puts his hand into the bag and pulls out a random ball and throws it away. If the ball is red, he makes a step towards the pool and if it is blue...

Homework Statement Between which two orbits of the Bohr hydrogen atom must an electron fall to produce light of wavelength 954.8 nm ? Homework Equations E = hv E = R(1/n1^2 - 1/n2^2) The Attempt at a Solution I've got it down to the differences in the reciprocals of the squares...

I want to design a model for falling spheres in a Newtonian fluid and I just want to make sure I've got everything right. Are these all of the forces that apply on an object in a liquid? I have the following formulas...

A person goes skydiving. The plane is one kilometer up and they decide to fall a height of 1.2 kilometeres before opening their chutes. How fast are they going at that point? Isn't it 9.8 m/s^2 because gravity has to be dragging them down at that rate? Thank you!

This relates to the thread "https://www.physicsforums.com/showthread.php?t=431712"" started by Passionflower, but is hopefully even simpler (but non trivial). The basic question, is what is the length of a falling elevator (or ruler) that is reasonably rigid, according to: 1) A...

Homework Statement Okay so the question is..A stone falls from rest from the top of a cliff. A second stone is thrown downward from the same height 3.99999 seconds later with an initial speed of 78.3998 m/s. They hit the ground at the same time. How long does it take the first stone to hit...

How do I calculate for velocity of a falling object through any medium at any given time if I have to consider both buoyancy and viscous drag. If I consider Newtons law , I assume that it would be something like m(dv/dt)=Fnet =mg-Drag-Buoyant force Am I supposed to get a...

A hot air balloonist rising vertically with a constant velocity of magnitude 5m/s releases a sandbag at an instant when the balloon is 40m above the ground. After it is released the sandbag is in free fall. a) Compute the position and velocity of the sandbag at 0.25s and 1s after it is...

Homework Statement This is from Serway's book Prob 9.71...(busying preparing for GRE) A chain of length L and total mass M is released from rest with its lower end just touching the top of a table, as in figure (a). Find the force exerted by the table on the chain after the chain has...

A lander is descending to land on the moon. The engine is cut off when the lander is 5.0 m above the surface and has a downward speed of 0.8 m/s. With the engine off, the lander is in free fall. What is the speed of the lander just before it touches the surface? The acceleration due to gravity...

If I am in free-fall towards Earth or in this case let's use a planet with no atmosphere to get rid of air drag. So I am in free-fall and then I throw a ball up above me. From my point of view the ball would appear to keep going away from me until i hit the ground. Is this correct?

As I understand it, clocks run relatively slower the closer they are to the center of a "gravity well" and also each other clock for a pair of observers moving relatively to each other appears to be running slower, relative to each frame of reference. So, start with a pair of highly accurate...

Homework Statement A cargo plane is flying horizontally at an altitude of 11.5 km with a speed of 860 km/h when a large crate falls out of the rear loading ramp. (Ignore any effects due to air resistance.) (a) How long does it take the crate to hit the ground? Homework Equations...

Homework Statement A ball is dropped from a height h. The ball displaces 0.47h meters from the time it hits one second before it drops to the ground and when it hits the ground. Find h. Homework Equations xf-xo=vot + 0.5gt^2 The Attempt at a Solution h = ? t1(at 1 second before...

Fluids doubt...water falling from a tap When water falls from a tap its area of cross-section is supposed to decrease progressively in accordance with the equation of continuity A1V1=A2V2 in order to maintain the conservation of mass. But using another line of thought, every particle in a...

I love to know how electricity is usefuel for us, electric cars, lighting and refrigeration, i love physics but i also like to know what the universe is made of, how is that a bunch of cells and we think! dam! i love chemistry. I also like solar panels and would like to really know how they...

I m solving the problem in which the drop is falling from some height and its size is increasing with the rate dm/dt=kMv where v is the velocity of the drop at that instant , so we have to find the terminal velocity of the drop gained due to air drag, The problem is that if the drop gains...

Homework Statement OK... Hammer falls from building and after 1 second has fallen 1 story... How FAR has it fallen after 2 seconds? Homework Equations d= s x t The Attempt at a Solution So, doesn't that mean the Average Speed for 1 sec is 1 story/sec? How do I calculate...

If i have a rod of length L at rest . And there is a hole up ahead that is L/2 and I move the rod at a velocity which will contract it to half its rest length. Will the rod fall into the grate? Well I think that from the rods point of view its still its rest length and it would appear...

Homework Statement A stone is dropped from rest at an initial height h above the surface of the earth. Show that the speed with which it strikes the ground is v=sqrt(2gh) Homework Equations The Attempt at a Solution I'm just not sure where to get started. I fully understand...

Just in case you are wondering, the "I am falling down a deep cliff" was something I got from "The Catcher in the Rye", I hope I used it correctly in my problem. Background on Problem I am a college freshman this fall and I am face with an undecided decision (that was very wordy). I have...

I've studied the basics of this in a physics textbook, and have searched on this forum, but one thing about this escapes me. My understanding is that a satellite is elevated somewhere above the Earth's atmosphere where air resistance is negligible. The satellite is then accelerated to a very...

Suppose a (uniform) chimney began falling. Where would the chimney break? I approached the problem by considering the torque acting on a point along the chimney, at a distance x from the point of rotation. I got the internal torque + external torque = (mx^2)(3gcosA/2L), where A is the angle...

I'm trying to derive the equations of motion for a particle falling in a uniform gravitational fill with air drag proportional to the square of velocity. However I'm getting the velocity as a complex number. Here is what I've done The force of friction is...

Hello guys. This is not really a homework exercise, but I'm currently preparing for an exam and this is a question I got from a textbook. I'm currently sort of stuck, but here are the details. Homework Statement Link to a scan of the problem...

Please help! I've been both conceptually blocked for quite some time and need help fast! A rock is dropped from a sea cliff, and the sound of it striking the ocean is heard 4.0 later. Given the speed of sound is 340m/s, calculate how high the cliff is in meters.

Homework Statement A rod of length L and mass M is pivoted about one end. The rod is released from rest in a horizontal position, and allowed to swing downward without friction or air resistance. When the rod is vertical, what is its angular speed w? Homework Equations Moment of Inertia...

I am not trying to propose any personal theories I am just trying to understand currently accepted physics. I have heard various descriptions of what would happen as you fall into a black hole. They usually end in spaghettification and eventually falling into the singularity itself. I...

One of us said: A metal ball and wooden ball regardless of weight and radius will hit the ground at the same time when dropped from any height (building) Second thing... is the speed of bullet exiting the barrel pointing upwards the same as it's speed when it hits the ground?

Hello, I’m glad that I found this forum, because there is a question that has been bothering me for some time, and maybe someone on a physics forum like this can set me straight on it. It concerns gravity and acceleration. I understand that when an object such as a space shuttle is...

Hi guys, In light of my upcoming flight to a tropical island, I would like to ask about a scenario that I've wondered about for ages. >>>NOTE: It's really ridiculous<<<< Okay, let's say the plane falls apart at an altitude of 30,000 feet and you are in free fall... Let's say that you were...