# Tagged Questions

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### How can I solve this differential eqution with IVP? [duplicate]

$$m\frac{d^2r}{dt^2}=-G\frac{Mm}{r^2}, \qquad r(0)=R ,\qquad \dot{r}=v_0>0$$ describes the free fall of an object of mass $m$. $r(t)$ is the distance of m to the center of the earth which is $R$ ...
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### Why does it hurt more to fall from 10 stories, than 1?

$F=ma$. Falling from any distance, mass stays the same, and acceleration due to gravity stays the same. So, why does it hurt more, the longer you fall?
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### Why does the mass of an object on a frictionless surface matter?

I'm given a physics problem about a climber hanging over a cliff and attached by rope to a rock on level, frictionless ice. The goal is to find the acceleration of the pair. After working out the net ...
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### Free-Falling Object

How does the presence of air affect the rate at which a body falls? What is the rule for falling objects, when there is little or no air resistance?
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### Does mass distribution/center of mass affect free fall?

An everyday is example would be cars. If you were to drop a car, not taking air resistance into account, would a front-heavy car tumble forward as it fell? And a car with a perfect 50/50 front/rear ...
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### Free fall for a longer time

When I'm in free fall, I'm weightlessness for only about 1-2 seconds. Is there any way I can feel weightlessness for a longer period of time?
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### What happens when an object is dropped from a very tall tower?

The critics against Copernicus and Galileo argued that, if the earth moved, then, a heavy body that was dropped from a very high tower should fall to the west of the foot of the tower. Galileo argued, ...
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### How do these factors affect the free fall of objects?

Take an example of two balls of different masses being dropped from about 250 meters from the ground. How do the following factors affect free fall: Air resistance. Absence of air resistance. ...
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### Acceleration due to Gravity: Free Fall [duplicate]

If we are in a free fall which implies we are accelerating at 9.8 m/sec every sec. And let's say that we are falling into a pit that has enormous depth. So isn't this be possible that we may ...
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### Relativity of simultaneity in Galileo's Leaning Tower of Pisa experiment

Galileo's conclusion can be roughly summed up as: objects of different masses, when dropped from the same height, descend in the same time interval, independent on their masses (neglecting friction). ...
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### General Relativity view of Newton's apple

If one considers the free fall of an object of mass $m$ from a hight $h$ in the Earth's gravitational field (neglecting air friction) from the point of view of GR, what would be the main corrections ...
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### How do a ball bounce in air?

An unclear case happened in Fenerbahce-Galatasaray football match last night. Galatasaray's striker Burak Yilmaz hit the ball when he was front of goalkeeper. Something happened while ball in free ...
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### Freefall into snow

In the movie Frozen, the following dialogue takes place: Anna: "It's a hundred-foot drop." Kristoff: "It's two hundred." Anna: "Okay, what if we fall?" Kristoff: "There's 20 feet of ...
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### What physics concepts support the observation of the book and paper falling together?

you place a sheet of paper on a book, it falls with it rather than being separated & slowed by air resistance. What physics concepts support the observation of the book and paper falling together?
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### How can we prove simply that acceleration for every freely falling body is equal to $g$? [duplicate]

If I allow two bodies of different masses to fall freely from same height towards the earth, how can I prove that the acceleration produced in both was constant and equal to gravity.
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### What is the relationship between the Young's modulus of a material and the elasticity of a free fall collision

I'm coding a 2D physics simulator based around the Newtonian physics principles with some alterations due to computation limits and I am at the stage of creating a collision event between a planetary ...
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### How much time would it take for a free-falling ghost-like object to cross the entire Earth? [duplicate]

We have an object of mass $m$ which can go through matter like a ghost. It's only affected by gravity, not by any other force, so it's in free fall. At the instant $t=0$ it is at the surface of the ...
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### Maximal Velocity of an Object in Free Fall

A baseball is dropped from a high point. Since the velocity is large, we can say that the drag force is proportional to the square of the velocity, $F_d = \gamma v^2$. My goal is to determine the ...
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### Gravity and bottomless pits [duplicate]

Assuming that someone is theoretically able to make a hole through the center of a large planet, and then jumps down the hole, what will happen? Given my understanding of gravity and energy, my ...
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### What would happen if you dropped iPhone from Outer Space? [closed]

I read this article where the title suggests the iPhone was dropped from space, but it looks more like it was dropped from an airplane I would think that if astronauts dropped an iPhone from space ...
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### Are time and gravity affected when at rest compared to free fall?

A falling object moves along a geodesic path ('straight path') in spacetime. When it comes to rest it now follows a 'curved path' through spacetime. Is the passage of time and force of gravity ...
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### Curved paths through spacetime when standing still?

I have heard that falling objects fall at the same rate irrespective of their mass. They are 'following straight line paths through curved spacetime'. Does this mean that objects that accelerate in ...
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### Mountain and a feather dropped from same height. Which hits Earth first?

Let's assume: the feather has a mass of $0.006$kg the mountain has a mass of $6 \times 10^{15}$kg the earth has a mass of $6 \times 10^{24}$kg no air resistance both objects released at the same ...
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### Dropping Objects of Different Masses

It's a commonly taught principle that dropping two objects of different mass at the same height, given that there is no air resistance, will result in the two objects making contact with the ground at ...
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### A falling object's position [duplicate]

I have asked this previously, with a very useful answer but I was not able to solve my problem. I'll try to make it more simple, basically: Find the radius, $r$ of an object after a time, $t$ if ...
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### How to expand this equation considering acceleration due to gravity into 3D vector space?

How can we expand this following equation into 3D vector space? I learned this equation from this answer: Don't heavier objects actually fall faster because they exert their own gravity? The ...
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### A Special Case About Projectile Motion [closed]

There is a common fact about projectile motion. Let me remind you with an example: Assume that you are aiming at a hanging banana on a tree. If there were no gravitational force, the bullet would ...
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### Was Aristotle Actually Correct About Gravitation? [duplicate]

Apparently, Aristotle reasoned (without experimentation) that heavier objects must fall to Earth faster than lighter objects. For example, a 1,000 kg ball of iron would fall faster than a 1 kg ball ...
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### Car driving / falling off of a cliff - will it land upright?

In a recent episode of The Walking Dead, a van was pushed off of a bridge and flipped once and landed upright, on all four wheels. Assumption: the ground and cliff are both flat. Will a vehicle ...
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### Is it possible to create a parachute large enough to stop all velocity?

This idea came to me while playing Kerbal Space Program. I noticed that the larger my parachute was, the slower my rocket would fall back down to Kerbin. I would like to know if it is possible to ...
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### Different density objects falling on Earth's atmosphere?

So I finally understood why 2 objects with different masses, free falling from the same distance reach Earth's surface at the same time (due to the objects Inertia). Now when the objects fall in the ...
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### How to explain that initial speed is zero?

I was trying to discuss about free-fall with a friend, who is not scientifically literate. The first hurdle came quickly and unexpectedly as I was trying to demonstrate that the speed of free-fall is ...
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### Would you die before reaching the ground?

If you were to jump off a tall building, let's say Burj Khalifa, is it true that the pressure difference would be so strong as to kill you before reaching the ground?
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### What acceleration to use in this problem?

A balloon starts rising from the ground with an acceleration of 1.25 m/second square. After 8 second, a stone is released from the balloon. Find the time for stone to reach ground, distance covered, ...
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### Acceleration of an object dropped inside an accelerating elevator

A stone is released from an elevator going up with acceleration of $g/2$. What is the acceleration of the stone just after the release? The answer is $g$. Shouldn't the stone carry the acceleration ...
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### What is the final velocity of a stone dropped out of a rising balloon? [closed]

A balloon is starting from the ground has been ascending vertically at uniform velocity for 4 sec and a stone let to fall from it reaches the ground in 6 sec. Find the velocity with which the stone ...
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### Is the Moon freely falling towards the Earth?

The Moon is revolving around the Earth and its centripetal acceleration is towards the Earth. Does it mean that the Moon is freely falling towards Earth? What is the cause of the Moon orbiting around ...
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### Why can a ball tossed up object free fall upwards?

I've found many websites that say that a ball tossed upward would be free falling upwards, but none of them say why. If the definition of free fall is an object that is falling while only under the ...
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### Impact force in a fall

I'm a climber and I constructed myself an anchor that I fixed to a rock wall. To test it, I hooked to it a 12mm in section steel cable with a length of 2,8m and a concrete block of 30kg to the other ...
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### Free fall and projectile motion

I'm wondering if something is falling say from a roof, would the distance it falls be the final $y$ position? Also would all the $y$ components (velocity, displacement) be negative?
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### Two Dimensional Kinematics and Projectile motion [duplicate]

I have a question. So a baseball is hit with a velocity of 30 m/s at 42.6 degrees to the ground. A fielder who is supposed to catch the ball is smart and knows that he is exactly 8 meters from where ...
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### Finding the velocity of a ball thrown upwards [closed]

A ball is thrown upwards with a speed of 16.1 m/s. What is the ball's velocity 1.6 seconds after it is released? I tried to solve this using the equation: $v = u+at$, substituting u for 16.1, a for 9....
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### At what speed would you die upon impact with water?

If we hit the water at great speeds, we die. This is because the water has no time to "move out of the way" and acts as a "solid" surface. At what falling speed can we consider the water as a 'solid'...
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### Measuring mass by acceleration due to electromagnetic forces in free fall

My question is a simple one (I think): How precise will the results be if you attempt to measure the mass of a macroscopic object by measuring it's acceleration when a constant electromagnetic force ...
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### Why is acceleration constant in this example?

I was shown this video by our professor: https://www.youtube.com/watch?v=8A7DiGzJUvg&feature=youtu.be And I do not understand why the acceleration is constant. Our professor told us that a freely ...
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### Tidal forces in free fall

Would a body free falling in a gravitational field which has a gradient large enough that it would affect the free falling body 'feel' the effect of the tidal forces on it. I'm curious because would ...
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### Which ball touches the ground first?

This is a very well known problem, but I can't find an answer in the specific case I'm looking for. Let's consider two balls : Ball 1 weighs 10 kg Ball 2 weighs 1 kg Balls have identical volumes (...
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### Is it really okay to treat the Earth as stationary when doing free fall experiments?

Typical treatments of free-fall experiments treat the the Earth as fixed. Using this model, object being dropped moves toward Earth, but the Earth doesn't move toward the object. A more detailed ...