P2 Flashcards
What are ways to measure time?
Use a stopwatch
Use light gates
What are ways to measure distance?
A ruler
Ultrasound
Rotating metal disk
What is the equation for speed?
Speed = distance / time
What is the difference between scalar and vector?
Scalar - just the magnitude (size)
Vector - magnitude and direction
What is the difference between distance and displacement?
Displacement is a vector so takes into account direction.
Distance is a scalar
What is the difference between velocity and speed?
Speed is a scalar quantity
Velocity is a vector quantity
What is acceleration?
Change in velocity per second
Uniform acceleration means the acceleration doesn’t change
What is the equation for acceleration?
Acceleration (m/s^2) = change in velocity (m/s) / time (s)
How do you find the speed in a distance-time graph?
The gradient of the graph
What does a straight line on a D-T graph mean?
Constant speed
Or
Not moving
What does the gradient of a velocity-time graph mean?
The acceleration
How do you calculate distance/displacement on a V-T or S-T graph?
The area underneath a speed-time graph is the distance
Area underneath a velocity-time graph
What is the equation of motion?
v ^2 - u^2 = 2as
v = final velocity
u = until a velocity
a = acceleration
s = distance
What is the equation for kinetic energy?
kinetic energy (J) = 0.5 x mass (kg) x velocity^2
What happens with pairs of forces?
- each force on a different object
- forces are the same size and type
- forces act in opposite directions
What are non-contact forces?
Forces that interact without being in contact, e.g:
- electrostatics
- magnetism
- gravity
What is a free body diagram?
Diagram that shows the forces acting on an object
Object is represented as a dot
What is Newton’s first law?
“An object will continue to stay at rest or move with uniform velocity unless a force acts on it”
A resultant force must act in the object
Principle of inertia
What is inertia?
Measure of how difficult it is to change the velocity of the object
What is equilibrium?
When the resultant force is 0
What is Newton’s 2nd law?
F = ma
Acceleration of an object is directly proportional to the force and inversely proportional to the mass