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!!
