bridge constructor playground tutoria bridge 8

Bicycle brakes work due to the fact that they are based on a lever. The effort is quite simply the amount of effort used to push down on the rod in order to move the weight. The load is the scientific name for the weight. Person lifting weight using a lever system The fulcrum is the place where the rod pivots (or rotates). Under normal circumstances the person would not be able to lift the weight at all. The longer the ‘rod’ the easier it is to lift the weight. In the example below, the heavy weight on the left hand side is been lifted by the person because of the lever. Levers are used to lift heavy weights with the least amount of effort. When a structure bends like this it is in tension as it is being stretched.įorces act across the entire length of the beam Levers In the diagram below, forces act across the entire length of the beam (it bends because of the ‘ton’ weight). Why is the pole under a compressive force ? The wires on either side of the flagpole are being stretched (tensile force). The floor beam is being stretched (tensile force).

The roof beams are under pressure from the weight of the tiles on the roof (compressive force).

The weight of the beam is stretching the rod (tensile force). The beam is held in position by a steel rod. The part of the structure that has a tensile force acting on it is called a TIE and the part that has a compressive force acting on it is called a STRUT. Struts and TiesĪll structures have forces acting on them. As the bridge bends, the top member is compress (under a compressive force). The diagram shows that the member that the car rests on is under tensile force (in tension) as it stretches under the weight of the car. When a vehicle crosses the bridge each member experiences some type of force. They are bolted together and are semi-permanent structures. The Royal Engineers have transportable bridges like the one above that can be dismantled and transported anywhere in the world and reassembled. This type of bridge is favoured by the British Army. The weight is distributed through all the members and so the bridge can cope with large weights. Triangulation distributes the weight of any vehicle or pedestrian crossing the bridge. The triangular shapes give the bridge immense strength and for short spans this type of bridge is ideal. Usually they are manufactured in a factory and transported to the site and dropped into position by a large crane. These are usually made of steel with all the members (parts) welded, bolted or held together with rivets. The bridge below is a common type called a Box Girder Bridge. Side “D” is stretched whilst side “C” is compressed. The vertical leg support of the playhouse bends inwards when weight is applied to the balcony area. Weight of user on playhouse balcony compresses the support beneath. When items are placed on etc shelf they weigh down on it applying stretching force to the tie support Kids playhouse with forces applied Forces on a Shelf With a Tie Support in Detail Part C and D: These forces are applied to the same member but on the inside compression is taking place and on the outside it is being stretched (under tension).Part B: Is under compression because the weight of the user when standing on the balcony are pushing downwards and compressing the strut.Part A: Is in tension because the weight of the shelf and items on it is stretching it and pulling it down.Using a kids treehouse/playhouse (when the balcony is subjected to weight) and a shelf in a kitchen we can see some different forces at work: The ruler is said to be in a state of torsion.

The plastic ruler is twisted between both hands. The force applied to the pin is called SHEAR FORCE. The two handles put force in different directions on the pin that holds the two parts together. The weight lifter finds that his body is compressed by the weights he is holding above his head.Ī good example of shear force is seen with a simple scissors.

This stretching puts the rope in tension. The rope is in “tension” as the people pull on it. The air pressure inside it pushes back against the weight. The tyre in the image below is filled with air and under great pressure. He is carrying a weight of books but walking. The force downwards is STATIC FORCEĪ good example of a dynamic load is the person below. He is holding a stack of books in front of him but he is not moving. A good example of this is a person seen below.

Bridge constructor playground tutoria bridge 8