I`ve personally never come across objects moving at constant speed.With forces of gravity acting everywhere,i do not see where this theory would apply in reality.Please help.Genuine answers please?Thanks.
2006-07-20 05:04:21 · 12 answers · asked by mamanoelia 3 in Science & Mathematics ➔ Astronomy & Space
Newton's 1st law is the relationship of inertia. "An object at rest will stay at rest unless acted on by a force. An object in motion will stay in motion unless acted on by a force." The law does not mention constant speed,since Newton's second law defines a force as an acceleration applied to a mass. Acceleration,by defintion, indicates a change in either speed or direction.
The biggest signs of this in the real world are friction and gravity. Friction keeps cars on the road and prevents us from sliding on frictionless surfaces most of the year. Gravity accelerates us toward the center of the earth and moves most of our water.
2006-07-20 05:13:51 · answer #1 · answered by C.W. 2 · 5⤊ 3⤋
The law is perfect. The object stays in motion until acted on by an equal and opposite force--Gravity and the friction with air and earth. The smaller the force the longer it has to act, the greater the force the less time it has to act. The opposite is also true the more time you use the less force you need etc. This is important because as you reduce friction you increase efficiency. It would take 0 gallons of gas to move a car 10,000 miles once it was already moving, if you could eliminate all friction. It is also important to consider when you are driving though. It's the reason you wear a seat-belt. A seat-belt puts a large force on the body but it does so in the areas of the body that can take it.
A practical application of newtons first law
New seat-belts can actually increase the amount of time your body is acted on by that opposite force by sucking in fast and then letting out "slowly" when your car is hit.. This reduces the intensity of the force.
Crumple zones are another practical application. They increase the amount of time/distance a smashed car takes to stop. Once again this decreases the intensity of the force on your body.
roller coasters, I'm not even going to explain.
Large trucks: It takes larger brakes to stop them because of Newtons first law.
Football players and all other sports for that matter.
Billiards
Boat anchors. A 5 pound anchor would not provide equal and opposit force to keep a tanker ship in one place now would it?
Suspention bridges or any other structure must be built so that the supports are strong enough to provide a force that is equal to the force of gravity pulling it down. This keeps the building still.
Basicly everything that we do that involves motion or even stillness, involves newtons first Law.
2006-07-20 12:10:35 · answer #2 · answered by goose1077 4 · 0⤊ 0⤋
Newtons first law of motion is true, however the problem is that there are always other forces that are acting on moving objects, so that can't continue moving indefinitely. For example, when you slide or roll something across a flat surface, the force of friction slows down the object. And if there's something like a paper airplane, the forces of air resistance and gravity will make the paper airplane slow down and fall.
So yes, Newton's First Law does apply, but there is no ideal place in the universe to test the theory to see if it's true. Basically, it's just there to show that there are other forces that act upon everything.
2006-07-20 12:10:30 · answer #3 · answered by Archangeleon 3 · 0⤊ 0⤋
The reason you don't see this in everyday life is because there are forces constantly acting on this object you see moving; ie gravity, friction etc. If there were no forces acting on the object it would move in a "straight" line at constant speed. An OK example would be an air hockey table. If you give the little puck a little push it will travel at "constant" (not really constant because of forces but close enough) speed.
2006-07-20 12:12:23 · answer #4 · answered by Bing 2 · 0⤊ 0⤋
Ok, Take driving in traffic. If everyone is doing a constant speed then there are no problems. When one Moron decides to slam on the brakes or change lanes all of a sudden then Newtons law comes into play. Classic Newton example is if you are the car in front you are in great shape. If you are in the car in the middle you just got squashed by a semi if you were in the car in the back doing your makeup then your Head you just kissed the airbag and your eyeliner is in your eyeball.
Hope this helps.
2006-07-20 12:11:26 · answer #5 · answered by Anonymous · 0⤊ 0⤋
You actually see it everyday. since the first law states that an object travels at a constant velocity and at one direction unless a force is applied. The whole statement is actually an "either-or" statement, meaning you either have constant motion or you have a force involved and a change in the state of motion.
2006-07-20 12:41:32 · answer #6 · answered by dennis_d_wurm 4 · 0⤊ 0⤋
Revolution of earth , Revolution of satellites, moon never stop because NET force acting on them is zero
these are examples of Ist law of motion
2006-07-20 13:36:30 · answer #7 · answered by shyam 2 · 0⤊ 0⤋
and you wont because there are always forces on earth acting on the object. Here is a nice website that goes over it and gives some everyday examples of how the law is at work.
http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/newtlaws/u2l1a.html
2006-07-20 12:10:06 · answer #8 · answered by Anonymous · 0⤊ 0⤋
Air hockey. Or ice hockey. The puck slides with very little friction and demonstrates the 1st law quite well.
2006-07-20 12:09:20 · answer #9 · answered by campbelp2002 7 · 0⤊ 0⤋
It applies in space, where you don't have gravity. The space missions to the planets are possible because once the ships get up to speed, they don't need any power to keep going.
2006-07-20 12:27:16 · answer #10 · answered by nursesr4evr 7 · 0⤊ 0⤋