In this chapter of AS/A-level Physics, you will learn about Mechanics.

Mechanics

Scalar --> magnitude but **no **direction (mass, temperature, time, speed, energy)

In AS/A-level Physics, Vector** --> Both **magnitude and direction

Representing vectors:

1. Length of the arrow represents magnitude

2. Direction of the arrow represents the direction of the vector

Vector addition

- Vectors along the same straight line F2

- Resultant = F1 + F2

Combining perpendicular vectors

- To find the resultant of two vectors (X, Y) acting at 90° to each other we draw vectors as adjacent sides to each other. This is due to the horizontal and vertical components being independent

- Magnitude of R can be worked out by R^2 = Y^2+ X^2

- In AS/A-level Physics, Direction of the angle 𝜃 is worked out by tan 𝜃 = Y/X

Vector subtraction

What is the boxes ∆ in speed?

o Change in speed = new – old

--> 10 – 6 = 4ms^{-1}

What’s its change in velocity?

o ∆inV=new velocity–old

o 10m/s (up) – 6 m/s down

o therefore --> 10 – (-6) = 16m/s as down is negative

In AS/A-level Physics, Vector subtraction is the same as the addition of a vector of the same size acting in the opposite direction

Combining on perpendicular vectors by calculations

1. Resolve the 3N like its horizontal and vertical

Horizontal --> 3xcos 30=2.6N

Vertical --> 3 x cos 60 = 1.5N

2. Replace 3N component

3. . Use Pythagoras and trig Resultant = 4.9 at 46°

That's it! You got it!!