Physics P1 Flashcards
What is a physical quantity?
A measurement of something and it’s unit
SI base units
(length, mass, time, current, temp, amount of substance)
Length - metre (m)
Mass - Kilogram (kg)
Time - second (s)
Current - Ampere (A)
Temp - Kelvin (K)
Amount of substance - Mole (mol)
How do you derive units?
Put together the units from the equation that make the physical quantity
What is a scalar of quantity?
A quantity that only has magnitude
What is a vector quantity?
A quantity that has magnitude and direction
Give 8 examples of scalar quantities
Distance, speed, time, area, volume, mass, energy, temperature, electrical charge, frequency
Give 5 examples of vector quantities
Displacement, velocity, acceleration, momentum, force, weight
How do you calculate the resultant force of a vector triangle?
Use Pythagoras theorem
What does resolving a vector mean?
Separating the horizontal and vertical velocities as mutually perpendicular components
Components of a vector
- Velocity in the x-direction = Fcos(0)
- Velocity in the y-direction = Fsin(0)
- Angle made by the vector = tan(0)=x/y
How to add non-perpendicular vectors
- Make sure/ rearrange the horizontal and vertical velocities head to tail
- Create a vector triangle
- Use the sine or cosine rule to find the resultant force
What is the cosine rule?
a^2 = b^2 + c^2 - 2bc x cos(A)
What a the sine rule?
a/sin(A) = b/sin(B) = c/sin(C)
How do you measure the distance travelled by an object?
A meter rule or a measuring tape
Define speed
The rate of change of distance
What is the gradient in a distance time graph?
The speed
Define displacement
The distance in a given direction
Define velocity
The rate of change of displacement
How do you calculate velocity?
Change in displacement/time taken
In a displacement-time graph, what is the gradient?
The velocity
In a displacement-time graph, what does a negative gradient represent?
Motion in the opposite direction
What does the gradient of a curve represent in a displacement time graph?
Drawing a tangent on a curve determines the instantaneous velocity
Define acceleration
The rate of change of velocity
How do you calculate acceleration?
Change in velocity/time taken