Vectors

Vector and Scalar quantities

• Scalar quantities have size or magnitude, but a direction is not specified.

(temperature, mass, speed, etc.)

• Vector quantities have magnitude and a specific direction (velocity, acceleration, etc.)

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The Resultant Vector

The resultant is a vector that represents the sum of two or more vectors.

One way to find a resultant could be to draw the situation to scale on paper (such as 50 m = 1 cm).

Measuring the length of the vector pointing from the tail of the first vector to the head the second vector, and then, multiplying by the scale .

For example if line (c) is 3.0 cm the distance would be 150 meters. This is the displacement.

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An example of the head-to-tail method of vector addition

Using Pythagorean theorem to find a resultants magnitude.

A toy car is moving directly across a moving walkway. As the car moves in the y direction, the walkway moves in the x direction.

• We can look at the diagram as a triangle. Therefore we can solve this by using the Pythagorean theorem.

Use the tangent function to find the direction of the resultant.

pg86 Physics Serway /Faugh (Holt)

pg86 Physics Serway

Other helpful right triangle functionsbesides tangent

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