# Vectors and scalars.

## Presentation on theme: "Vectors and scalars."— Presentation transcript:

Vectors and scalars

Demonstrate an understanding of the difference between scalars and vectors and give common examples
Add vectors by graphical representation to determine a resultant Determine graphically the resultant of two vectors

For your notes Define vector and scalar quantities
Give examples of each Add and subtract vectors

Scalar quantities only have magnitude (size)
Scalars Scalar quantities only have magnitude (size) e.g. temperature, speed, distance, energy, mass.

Vectors are quantities with magnitude and direction.
In pairs develop a list of vector and scalar quantities Which values can be negative? What about temp?

Drawing vectors Well duh Use arrows
Length of arrow represents magnitude of vector Direction represents direction of vector Well duh

An illustrative example
Speed vs velocity Consider a car travelling in a circle at a constant speed of 2ms-1 Comment in as much detail as possible on The speed The velocity The acceleration

Speed vs Velocity

Firing a bullet from a Plane
A plane flys at 610 ms-1 it shoots a bullet at 600ms-1. Does it shoot itself down? What is the velocity of the bullet?

E.g. Scale: 1 cm = 2 cm s-1 the magnitude of P can be calculated using Pythagoras’ theorem: P2 = vh2 + vv2 P Vh Vv

Parallelogram of vectors
Draw both vectors from the same point Complete the parallelogram The diagonal is the resultant Measure the length (magnitude )and angle

Also You can use a parallelogram drawn to scale to find the components of a force. The most useful components are perpendicular

Summary questions Define a vector and a scalar
Give 5 examples of scalar quantities Give 5 examples of vector quantities Draw a scale diagram to add a force of 3N at 30º to the horizontal to a force of 5N at 80º to the horizontal Resolve an acceleration of 2ms-2 at an angle of 25º from North into two perpendicular vectors.

Can you? Define vector and scalar quantities Give examples of each