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Vector


Primarygun

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A vector has magnitude with direction, scalar is just magnitude.

 

For instance, a car moving at 50km/h can be said to have a speed of 50km/h (scalar) but we could give more information and say its velocity is 50km/h northerly which is a vector.

 

Forces are vectors and the direction of the force makes the world of difference:

 

Force x acts on a body pushing forwards. Force y acts pushing it backwards. The resultant force is x - y. If they were pushing it in the same direction the resultant foce would be x + y.

 

Scalar values have no direction. A thermometer does not tell you in which direction temperature is travelling as this does not make sense. Scalars are things like temperature, pressure and speed.

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What's it mean by "The vector sum of any two of three forcecs in equilibrium must be equal and opposite to the third force"?

 

Ok, say the forces are all pushing on something, a ball lets say, from different directions. Its in equilibrium, meaning its all balanced out so the ball isn't moving. The 3 things pushing on the ball keep it in one place. If you take out one of thosee forces, it would no longer be in equilibrium and the ball would move. Since those two forces can be cancelled out by the third force, it means the two of them added together must be equal and opposite to the third. This works no matter which one you take out.

 

 

Uhh, I havn't really done much with vectors, and while I can picture and explain this in my head, im not so sure about words. This may be innacrurate on some level.

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What's it mean by "The vector sum of any two of three forcecs in equilibrium must be equal and opposite to the third force"?

 

Ok, say the forces are all pushing on something, a ball lets say, from different directions. Its in equilibrium, meaning its all balanced out so the ball isn't moving. The 3 things pushing on the ball keep it in one place. If you take out one of thosee forces, it would no longer be in equilibrium and the ball would move. Since those two forces can be cancelled out by the third force, it means the two of them added together must be equal and opposite to the third. This works no matter which one you take out.

 

 

Uhh, I havn't really done much with vectors, and while I can picture and explain this in my head, im not so sure about words. This may be innacrurate on some level.

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If you look at examples in a physics book of scalars, you'll see a common property that unites them to the category scalar.

 

If you look at the examples of vectors, they will have a common property that unites them to the category vector.

 

Scalars use only a one dimensional coordinate system, whereas vectors use a coordinate system with more than one dimension. This is the differing principle: one dimension (scalar) and more than one dimension considered (vector).

 

Consider the Cartesian coordinate system. There is the x, y and z axis. Single one out and it's only one dimension. Add two together and you get two dimensions. Add all three and you get three dimensions.

 

The word 'scale' sounds like scalar and is in the scalar category. A bathroom scale plate compresses a spring along one axis, which is one dimension, the 'y' axis and dimension, which is soley up and down. This spring causes the needle to move on the scale demonstrating the magnitude along the y axis, which is the linear displacement the scale plate moved from the point it was before you stood on it to after you stood on it.

 

When you play chess the Rook needs only one dimension to move during a turn, which is the x or y dimension. The Rook may move in either the x or y direction, but may not move in both on one turn. So, when the Rook does move, it relies on one dimension only. The Knight must rely upon two dimensions to move. It moves one or two spaces along one dimension then two or one along a separate dimension.

 

A thermometer soley measures magnitude along a linear axis. It is a scalar only because it considers one dimension of magnitude, which occurs along the number line(one dimension) where you read the temperature.

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