What is Falling object: Definition and 174 Discussions

In Newtonian physics, free fall is any motion of a body where gravity is the only force acting upon it. In the context of general relativity, where gravitation is reduced to a space-time curvature, a body in free fall has no force acting on it.
An object in the technical sense of the term "free fall" may not necessarily be falling down in the usual sense of the term. An object moving upwards might not normally be considered to be falling, but if it is subject to only the force of gravity, it is said to be in free fall. The Moon is thus in free fall around the Earth, though its orbital speed keeps it in very far orbit from the Earth's surface.
In a roughly uniform gravitational field, in the absence of any other forces, gravitation acts on each part of the body roughly equally. When there is no normal force exerted between a body (e.g. an astronaut in orbit) and its surrounding objects, it will result in the sensation of weightlessness, a condition that also occurs when the gravitational field is weak (such as when far away from any source of gravity).
The term "free fall" is often used more loosely than in the strict sense defined above. Thus, falling through an atmosphere without a deployed parachute, or lifting device, is also often referred to as free fall. The aerodynamic drag forces in such situations prevent them from producing full weightlessness, and thus a skydiver's "free fall" after reaching terminal velocity produces the sensation of the body's weight being supported on a cushion of air.

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  1. V

    When Will the Thrown Ball Reach the Ground?

    1. Homework Statement [/ [B]A ball is thrown directly downward, with an initial speed of 7.15 m/s, from a height of 31.0 m. After what time interval does the ball strike the ground? Homework Equations All the kinematics equations dealing with velocity and height and accelration. need to...
  2. O

    Free falling object and Newtons law

    A plane which is flying at constant speed v, and a height h, above the sea, must drop a bundle of supplies to a castaway of a small raft. a) write down Newtons second law for the bundle as it falls from the plane, assuming you can neglect air resistance. Solve your equation to give the...
  3. A

    Calculating time of falling object

    Homework Statement A person standing at the edge of a cliff kicks a stone over the edge with a speed of 20m/s. The cliff is 51m above the water. Gravity acceleration is 9.8m/s how long does it take the stone to fall and hit the water, answer in seconds Homework Equations D= Vi t +...
  4. C

    Motion of a freely falling object

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  5. M

    How Long Will the Volleyball Be in the Air?

    Homework Statement Jason hits a volleyball so that it moves with an initial velocity of 6.0 m/s straight upward. If the volleyball starts from 2.0 m above the floor, how long will it be in the air before it strikes the floor? Homework Equations y=-2.0m,Vi=+6.0 m/s a=-9.81m/s^2...
  6. mbrmbrg

    Falling object (gravity + kinematics)

    Homework Statement An object is dropped from an altitude of one Earth radius above Earth's surface. If M is the mass of Earth and R is its radus, find the speed of the object just before it hits Earth. Homework Equations F_g=ma_g=\frac{GMm}{r^2} v^2=v_0^2+2ah The Attempt at a...
  7. M

    Solving for Vertical Projectile Motion: Maximum Height, Time, Speed Formulas

    A ball is thrown vertically upward with a speed of 25.0 m/s. (a) How high does it rise? (b) How long does it take to reach its highest point. (c) How long does it take to hit the ground after it reaches its highest point? (d) What is its speed when it returns to the level from which it started...
  8. DaveC426913

    Rehash: speed of falling object at Earth's centre

    On another forum has appeared the ol' "drop a ball down a tunnel that passes through the Earth's centre" discussion. Someone has naively calculated the speed of the object at a ridiculous number - a fraction of the speed of light! I'm pretty sure their error is that they are not taking...
  9. E

    Energy created by a falling object

    Hello All I hope someone can help. I am dropping a weight on a bar to find out deflection of this bar. When I drop a 72lbs weight @ 1.0meter from the bar, the impact energy is (32.7KG x 9.8m/s2 x 1.0m) right? = ~311 N/m The total deflection when I drop this weight on the bar is 80mm. On...
  10. E

    Gravity Explained: Why Objects Fall

    My limited understanding of relativity tells me that "gravitational forces" are really just due to the curvature of spacetime. That is, the reason why the Earth orbits the sun is because the Earth is following a "straight" line but the actual spacetime is curved so the "straight" line appears...
  11. G

    Energy created by falling object

    If there is a 1.36 kg weight falling .1524 meters, how many joules are created when the object reachs the end of the .1524 meters. How do you calculate this? I came up with 2.032 joules which is .20723 kg meters which I think is enough power to lift 1.36 kg .1524 meters which is the same as...
  12. T

    How Does Kinematics Calculate the Trajectory of a Thrown Ball?

    Please tell me if I have done this correctly. A ball is thrown upward from the ground with an initial velocity of 10 m/s. Assume all digits are significant. a. How long before the ball reaches its maximum height? t = (0m/s - 10m/s) / -9.80m/s2 t = 1.0s b. What is the ball's maximum...
  13. E

    Initial Velocity of a falling object

    Hello everyone :smile: I know that \sqrt { \frac {2d} {g} } but what about including initial velocity? Thanks in advanced "Im the master of time" -- Eiffel 65
  14. J

    Force acted on a falling object.

    I was having a discussion with a friend and neither of us could come to a conclusion. The question is, what is the force acting on an object, by the ground, if it is released from a heigh? This is how we related it: If the object is on the floor, there is a weight and normal force acting on...
  15. M

    Solving a Quick Falling Object Problem in Physics - Simplified Solution

    Hi, I need help with a problem here at work. Unfortunately, I completely forget physics and dynamics. Here's the problem: I have a 1000 lbf object falling 32 feet. What is the impact force on the ground assuming that it stops instantaneously. I'm pretty sure I can get the number if I'm given...
  16. F

    Conservation of Momentum: Falling object

    Does a ball falling to Earth violate conservation of momentum?
  17. S

    Force exerted to stop falling object

    Having trouble with this problem: 3. [SFHS99 5.P.37.] A 50.0 kg diver steps off a 12.0 m high diving board and drops straight down into the water. If the diver comes to rest 5.0 m below the surface of the water, determine the average resistance force exerted on the diver by the water...
  18. E

    Finding Initial Velocity of a Freely Falling Object

    need help finding where to start, "A freely falling object requires 1.50sec to travel the last 30.0m before it hits the ground. From what height above the ground did it fall?" I know that: accel = -9.80m/s^2 avg. veloc for last 1.50 sec = 20m/s that i need the initial velocity for...
  19. S

    Determine velocity of falling object after certain time

    Need a little help on Kinematics. Say for instance, an object was dropped by a steadily rising body. To determine the velocity of the falling object after a certain time would be V(f)=(-9.81)(t). But if one were to find the distance between the falling object and the rising body, how could...
  20. T

    Settle a Dispute: Falling Objects & Relativity

    Hello to the board. I don't know a lot about physics or relativiity, but I'm here to try to settle a friendly dispute I'm having with a friend. He was taught that the mathematics of General Relativity state that an object doesn't fall to Earth, but Earth rises up to meet it. That flies in the...
  21. 4

    The Mechanism of Falling Object: no gravity

    The mechanism of falling object is always an interested topic. Almost all physicists think that gravitational force acts on object and makes it have weight and free fall. Here a very simple experiment negates the above parlance. Galileo demonstrates that different mass bodies increased their...
  22. D

    Does Density Affect Falling Object Speed?

    Disclaimer: Dont hurt me, I am not exactly a physics nut or anything, and what I am about to say has probably been figured out, its just that I thought of it, and I never heard anything of it before, soooo... Problem:If two objects were dropped from a height with the same texture, shape...
  23. D

    Effective Weight of Falling Object

    I'm am trying to determine the effective weight of a branch that falls from a tree to the ground. When I say the "effective weight" I mean the effect of the increased speed of the branch as it falls. The branch would fall from say 30 metres (say 90 feet) and would initially weigh 1 kilgrams...
  24. I

    Falling Object at c: Relativistic Position Expression for the Attracted Object

    Gedenke experiment: Falling object upto c? Bonjour, I would like to know the relativistic position expression for a falling object that could reach the speed of light. Thanks. P.S.: Suppose the only things, that exist in the universe, are a BIG attractive mass and the attracted "object".
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