OK, here's a question related to this thread. Assuming resistance is negligible, how could an object falling toward the Earth continue to accelerate indefinitely? I expect that landscaper might get this one.
What does this mean
- Thread starter Big Rig
- Start date
F=G*m(1)*M(2)/Rsquared
How could an object falling towards the Earth accelerate indefinitely? An excellent example is Skylab or the ISS. In orbit, these objects are moving with a velocity, but they are continuously accelerating towards the earth. It is this acceleration which is "bending" the trajectory. Every object will remain at rest or in constant motion unless acted upon by an outside force. So the satellites will travel IN A STRAIGHT LINE unless acted upon by a force. Gravity is a force. Gravity causes the satellite to "fall" towards Earth. But the velocity of the satellite is such that the Earth does not exert enough of a force that the object loses altitude. The forces are balanced, but because the object is constantly changing direction, it is constantly accelerating.
While the effects of friction are small, they are enough that sooner or later the object will have its "orbit decay" and the acceleration will finally cause the object to start moving closer to the Earth. The closer to the Earth, the greater the force of gravity and the greater the acceleration the faster the change in direction (towards the centre of the Earth).
If there is no other force acting upon 2 objects, the force of gravity will affect both and they will be pulled towards each other. In the case of Skylab vs the Earth, the mass of Skylab is so small compared to the Earth that it APPEARS to have no effect on the Earth, but that is only because we cannot measure the effect. As the two objects come closer, the force of gravity increases so that no only are the objects accelerating, but the rate of accelerating is accelerating.
The objects will continue to accelerate towards each other until they meet and merge.
Any object on the face of the Earth is in constant acceleration. It is continuously being pulled towards the centre of the Earth, and it is constantly moving due to the rotation of the Earth.
Do mountains get larger or smaller? They get smaller over time as rocks fall off and fall to the "ground".
OK I'll bite. Yes. The acceleration due to gravity we've discussed. To be pickily accurate—which most of us never need to be—it's the single relevenat factor only in a vacuum, or at the initial instant the object starts to fall. In ordinary air, from that moment on, there's the braking force of air; it's effect has to be subracted to get a calculation of true speed. Since the resistive force depends on the object's aerodynamics, there's no way to conveniently factor it into a general expression as there is with acceleration due to gravity. But that number should always have the phrase, 'in a vacuum' tagged on. When we're all that punctilious, there will be no further progress for mankind to make.
Strictly speaking you're right about mass and gravity, but the difference between the mass of the earth and anything much smaller than the moon makes it's effect on that falling object trivially negligable. But I'd bet somewhere in NASA there's someone who takes it into account calculating orbital decays.
All statements of measure are approximations. It's all a matter of picking the degree you need.
An object will accelerate due to gravity until it reaches the object exerting the force., ie you fall towards the earth until you go splat, the atmosphere provides resistance to the acceleration based on the drag of the object falling,. For example take two sheets of paper crumple one up into a ball drop both from the same height at the same time the crumpled paper ball will land first. That is air resistance, in a vacume both land at the same time.
There is also an esoteric limit to acceleration, an object cannot achieve the speed of light as a velocity due to several pages of mathematical proof, lets just say that Einstein has yet to be proven wrong( although I know of a couple of people who are working on that).
Thought experiment time, If you have an object far enough away exerting a gravitation attraction on a second object resulting in an acceleration of 10.0 m/s/s. In theory if the object is far enough away you could accelerate to beyond the speed of light. Butthat is not possible acording to Mr Einstein. ( and yes I know about the inverse square power/distance function ) It is an interesting thought experiment.
C = velocity of light, n = smallest velocity measurable.It is an interesting thought experiment.
You are travelling in a spaceship with the velocity of C-n and you turn the headlights on at the front of the ship. How much further will you see? Someone in the back of the cargo hold turns on a flashlight that it pointed in the direction of the movement of the ship. How much light will make it to the front of the ship? Some idiot in the back of the passenger section fires a Glock 10 mm in the direction of travel, how much damage will that bullet do to the ship?
There is no such thing as force of acceleration.
btw, how many of you guys in this thread are wearing shirt pocket protectors with 17 pencils, 2 pens and a scale in it? lol
Sorry, you are right. It should have been "the force causing the acceleration". I was lazy.
The OP was confused about why a falling object would fall with a speed of 32 ft/sec/sec, instead of just 32 ft/sec.
The 32 ft/sec/sec is a measure of acceleration, which is a rate of change of velocity. Think of it this way: changing speed at 32 ft/sec/sec is the same as changing speed at 22 miles/hour per second, or (this being Canada) at 35 km/hr per second.
Of course, real objects actually do fall at constant speed. Falling objects do not go on accelerating ad infinitum. The object encounters air resistance, which stops it accelerating beyond a terminal velocity. The TV for a human body is about 190 km/hr (120 mph). No matter how far you fall, you wont be doing more than 190 km/hr when you hit the pavement. You start off accelerating at 35 km/hr per second, then the rate of increase drops off as you apporach 190 km/hr.
The 32 ft/sec/sec is a measure of acceleration, which is a rate of change of velocity. Think of it this way: changing speed at 32 ft/sec/sec is the same as changing speed at 22 miles/hour per second, or (this being Canada) at 35 km/hr per second.
Of course, real objects actually do fall at constant speed. Falling objects do not go on accelerating ad infinitum. The object encounters air resistance, which stops it accelerating beyond a terminal velocity. The TV for a human body is about 190 km/hr (120 mph). No matter how far you fall, you wont be doing more than 190 km/hr when you hit the pavement. You start off accelerating at 35 km/hr per second, then the rate of increase drops off as you apporach 190 km/hr.
BRAVO i still actually own one, it would take a while to remember how to use it though.....
