Well, you use a screwdriver or a drill. The screwdriver is a type of lever that helps turn the screw into the wood. A screw is really just a cylinder with an inclined plane wrapped around it. The pointed end of a screw works like a wedge another simple machine!
A screw can function in two ways: it can raise up a weight, and it can fasten two or more objects together. An example of using a screw to raise a weight is when it is used to get oil. Oil coming from a deep well can easily be pumped out with the aid of the pumping screw.
Archimedes was a famous mathematician and inventor who more than two thousand years ago designed the Archimedes screw — a machine that was turned by horses or people to raise water. When we use a screw to fasten objects, the screw converts rotating motion of turning the screw into straight-line motion of the screw into wood or other material. That is what gives the screw its mechanical advantage.
It takes less force to turn a screw into a hard material than to pound a wedge into the same material. Engineers today use screws in many engineering applications and designs such as drilling rigs that bring up oil, dirt or water. Have you ever seen a car jack raise a car to help change a flat tire? Well, that is an example of a screw as well. Engineers also use screw as fasteners for large objects such as sports stadiums or airplanes, and for smaller objects such as desks or MP3 players.
Today we are going to take a closer look at two simple machines — the inclined plane and the screw. How do you think they may have helped build the ancient pyramids? Following the lesson refer to the activity Watch It Slide! The mechanical advantage of a machine is the ratio of the load to the applied force.
In other words, mechanical advantage determines how much force we need to perform a task. For example, the greater the mechanical advantage of a machine, the less force we need to have to perform a task such as moving an object. The opposite is true as well.
A good mechanical advantage is one that is greater than 1. The purpose of an inclined plane as a simple machine is to move something from a lower height to a higher height with less effort.
An object simply placed on a tilted surface often slides down the surface see Figure 1 because of the force in the downhill direction. In other words, the forces in this scenario are unbalanced i. The rate at which the object slides down is dependent upon how tilted the surface is; the greater the tilt of the surface, the faster the rate at which the object will slide down it. This is measured by the angle of inclination. Students can find this using a protractor. Friction also affects the movement of an object on a slope.
Friction is a force that offers resistance to movement when one object is in contact with another. Imagine now that you were on the downside of the object and applying force to keep the object in the same place not moving.
To keep the object stationary, the force you would have to apply would need to equal the downward force due to gravity. That would be an example of balanced forces. If you wanted to push the force upwards, you would need to exceed the force of gravity. Figure 1: This diagram shows how ancient cultures used inclined planes to move heavy stones to the top of their pyramids.
The force of gravity, friction and the pull force all affect how easy or hard it is to pull the cart up the inclined plane. To understand an object's motion on an inclined plane, it is important to analyze the forces acting upon it.
The force of gravity also known as weight acts in a downward direction. When the angle of inclination is greater, and the slope is steeper there is more weight component to overcome. With a shallower slope the weight component is easier to overcome and requires less effort.
The mechanical advantage of an inclined plane depends upon its slope and height. To find the ideal mechanical advantage of an inclined plane, divide the length of the slope by its height. An inclined plane produces a mechanical advantage to decrease the amount of force needed to move an object to a certain height; it also increases the distance the object must move.
The object moving up an inclined plane needs to move the entire length of the slope of the plane to move the distance of the height. For example, if you have a ramp with a slope length 20 meters that rises 5 meters high, then your trade-off is moving the 20 meters distance versus lifting straight up 5 meters, and your ideal mechanical advantage is 4.
A screw is a simple machine that has two purposes. It can be used to fasten two or more objects together or it can be used to lift up a heavy object.
In most applications, a lever is used to turn the screw. A good example of this is a screwdriver. It is the circumference of the lever or screwdriver and the pitch of the screw that determines the mechanical advantage of the screw.
The pitch of a screw is the distance between adjacent threads on that screw. The pitch can be calculated by dividing a certain distance by the number of threads on screw. One complete revolution of the screw into an object is equal to the distance of the pitch of a screw. The ideal mechanical advantage of a screw is found approximately by dividing the circumference of the lever by the pitch of the screw.
Today, we learned about two simple machines; the inclined plane and the screw. Who can give me an example of an inclined plane? Possible answers: Ramp, staircase, escalator. How does an inclined plane help us do work? Possible answer: We push objects up an inclined plane. What is the trade-off? Answer: Distance What are two ways screws are used? Answer: To fasten objects or to lift something. What other simple machine often helps us use a screw? Answer: A lever.
What has an engineer designed that uses an inclined plane or a screw? Possible answers: Parking garage, ramp, escalator, drilling rig, holding parts of something together, such as an airplane or MP3 player. In other lessons of this unit, students study each simple machine in more detail and see how each could be used as a tool to build a pyramid or a modern building.
To deviate from the horizontal. Usually a straight slanted surface and no moving parts, such as a ramp, sloping road or stairs. Making the task easier which means it requires less force , but may require more time or room to work more distance, rope, etc. For example, applying a smaller force over a longer distance to achieve the same effect as applying a large force over a small distance. The ratio of the output force exerted by a machine to the input force applied to it. The wheelchair begins at a lower level and rather than being lifted up to the higher level, a ramp is used to push the wheelchair up.
The distance needed to push the wheelchair becomes further, but the force and energy needed to maneuver the wheelchair becomes less. The same principle is used while using loading ramps to load trucks, planes and trains. A slide is another example of an inclined plane. Although largely used for recreational purposes, the slide is an inclined plane also used to lower heavy objects to a flat surface. Rather than dropping the object, it is slowly descended down the slide with less energy used and also a much safer result.
Stairs are inclined planes. In order to get to a higher level or another floor in a building or home, stairs become a plane traveled to accommodate the climb. Less energy is needed to walk the stairs than it would takes to climb up. Similarly, escalators are inclined planes that propel a person or object up a distance without exerting energy. Merely ride the inclined plane to the desired height and exit. A person climbs to the top and using the slippery water surface, that person accelerates themselves down the plane at exciting speeds.
The greater the inclined angle, the greater a speed is achieved. That is, all the individual forces are added together as vectors. The perpendicular component and the normal force add to 0 N. The parallel component and the friction force add together to yield 5 N. The net force is 5 N, directed along the incline towards the floor. The above problem and all inclined plane problems can be simplified through a useful trick known as "tilting the head.
Thus, to transform the problem back into the form with which you are more comfortable, merely tilt your head in the same direction that the incline was tilted.
Or better yet, merely tilt the page of paper a sure remedy for TNS - "tilted neck syndrome" or "taco neck syndrome" so that the surface no longer appears level.
This is illustrated below. Once the force of gravity has been resolved into its two components and the inclined plane has been tilted, the problem should look very familiar. Merely ignore the force of gravity since it has been replaced by its two components and solve for the net force and acceleration. Begin the above problem by finding the force of gravity acting upon the crate and the components of this force parallel and perpendicular to the incline.
Now the normal force can be determined to be N it must balance the perpendicular component of the weight vector. The net force is the vector sum of all the forces. The forces directed perpendicular to the incline balance; the forces directed parallel to the incline do not balance. The net force is N N - N. The acceleration is 2.
Sanders' Site. Inclined Planes An object placed on a tilted surface will often slide down the surface. The equations for the parallel and perpendicular components are: In the absence of friction and other forces tension, applied, etc.
This yields the equation in the absence of friction and other forces In the presence of friction or other forces applied force, tensional forces, etc. My Resources. Classroom News. My Homework. My Calendar. Kinematic Equations. Newtons 3rd Law. Notes on Acceleration Graphs.
Notes on Forces. Notes on Newtons 1st Law. Notes on Newtons 2nd Law. Notes on Vectors.
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