please i need this answered by 9:00 tonight because i have exams tomarrow and it's one of the questions. please help me
thank you
2007-05-31 11:57:04 · 8 answers · asked by summer_lover_13 1 in Science & Mathematics ➔ Physics
An inclined plane is a simple machine in that an object will be subjected to a force parallel to the face of the inclined plane equal to m*g*sin(th), where th is the angle of the plane w/r/t the horizontal. There is a resistance due to friction parallel to the slope. This can be modeled as cos(th)*m*g*µ, where µ is the coefficient of friction. If the object is stationary it is static, and if moving it is kinetic.
If you examine a screw, the threads are machined in a helical pattern on the shank of screw. When a torque is applied to the screw it wants to spin. If the screw is in threads, or a material it can penetrate, this spinning action causes the screw to move. If the threads are machined at an angle th, then for every complete turn the screw advances a depth of sin(th)*2*pi*r, or in radians, sin(th)*2*pi
The torque is equal to I*alpha, where I is the moment of inertia and alpha is the angular acceleration. There is a resistance to motion of the screw due to friction, which is related to the length of the surface of the thread, much like the parallel surface of an inclined plane.
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2007-05-31 12:01:46 · answer #1 · answered by odu83 7 · 0⤊ 0⤋
The BOTH are considered SIMPLE MACHINES.....
The other four "official" Simple Machines are
The Wheel and Axle
The Lever
The Pulley
The Wedge
However, once something gets into a text book wrong, it stays that way almost forever. There is a SEVENTH simple machine, the BOW STRING....
Picture a bow, pull the string. It is easy when you first start because you have a mechanical advantage, just like you do with ALL of the other simple machines. Now extend the idea to something larger.
Imagine a car out of gas and you have to move it by yourself. You tie a long rope to the bumper of the car and the other end to a tree as far away as you can get with the rope. Then you go to the middle of the rope and push sideways. As you start, you will easily be able to move the car but it will gradually get harder and harder until you hit a 90 degree angle with the rope, then you lose all your mechanical advantage.
The BOW STRING fits all the criteria for a Simple Machine but since it never got into the text books and teachers NEVER seem to go back and review the accuracy of the information, our kids are STILL being told there are only SIX simple machines..
Get a text book. Check it out. While you are doing that, look up airplanes and why they fly. I bet they give you that standard line about the shape of the wing and air flow over the wing creating lift. Yes, it does, but that is not why planes fly. If it was true, then how could a plane fly upside down?
2007-05-31 12:15:10 · answer #2 · answered by forgivebutdonotforget911 6 · 0⤊ 0⤋
A screw is an inclined plane wrapped around a central core. Just cut a right triangle out of a piece of paper. Use a 3 inch leg, a 10 inch leg and a hypotenuse connecting them. Place a pencil on the 3 inch leg and roll the triangle around the pencil until you reach the point where the 10 inch leg and hypotenuse meet. Now have a look at it. Does it look like a screw???
2007-05-31 12:11:32 · answer #3 · answered by gimpalomg 7 · 0⤊ 0⤋
a screw is a bolt or shaft with an inclined plane wrapped around it. Pulleys can be "added together" to create mechanical advantage, by having the flexible material looped over several pulleys in turn. More loops and pulleys increases the mechanical advantage. Another way to increase mechanical advantage is to reduce friction. A common way to reduce friction is by using a lubricant, such as oil, water, or grease, which is placed between two surfaces. In the instance of a pulley the flexible material, the cord or rope, would be lubricated so it moves more easily.
2016-05-18 00:01:23 · answer #4 · answered by Anonymous · 0⤊ 0⤋
a screw has an inclined plane on it that wraps around the shaft just like the red line up a barber pole.
This inclined plane on the screw lets it go inwards when it is turned.
2007-05-31 12:02:11 · answer #5 · answered by Anonymous · 1⤊ 0⤋
a screw is an inclined plane. stand a screw on end and see how the ribs angle either up or down. that is an inclined plane. in the screws case the inclined plane digs into the surface you want to puncture and because all of the inclines are angled up it pulls the screw down.
2007-05-31 12:10:59 · answer #6 · answered by TBEAR 2 · 0⤊ 0⤋
A screw is an inclined plane wrapped up around a cylinder. It is like a spiral staircase without steps
2007-05-31 12:03:01 · answer #7 · answered by anton p 4 · 0⤊ 0⤋
the thread of a screw winds around the body in an increasing spiral towards the top of the screw, this is in effect an inclined plane wrapped around a post.
2007-06-04 04:24:52 · answer #8 · answered by johnandeileen2000 7 · 0⤊ 0⤋