Unit 1 - Forces and Motion Flashcards
Explain what is meant by a scalar quantity. Give 2 examples.
A scalar quantity is a quantity with a magnitude (size).
-distance
-speed
-time
-mass
-energy
-temperature
Explain what is meant by a vector quantity. Give 2 examples.
A scalar quantity is a quantity with a magnitude and a direction.
-force
-velocity
-displacement
-momentum
-moment
Define speed, velocity, and acceleration
Speed is the distance travelled per unit time.
Velocity is speed in a given direction.
Acceleration is the change in velocity per unit time.
What is speed/velocity measured in?
Metres per second (m/s)
What is acceleration measured in?
Metres per second squared (m/s^2)
How to calculate average acceleration?
a = (change in velocity) / time taken
What is change of velocity? Give symbols
Difference between initial velocity (u) and final velocity (v)
Which property of a distance-time graph can be used to calculate speed?
The gradient (or slope)
What does the gradient in a displacement-time graph represent?
Velocity
What gradient (in a distance-time graph) shows constant speed?
Diagonal line (directly proportional)
For example:
/ or \
What gradient (in a distance-time graph) shows rest?
Horizonal line above x axis
What happens in a negative gradient of a displacement-time graph? ()
Negative gradient means returning back to starting point
What does the gradient in a velocity-time graph represent?
Acceleration
What does a horizontal line in a velocity-time graph represent?
Constant speed
How do you measure distance travelled in a velocity-time graph?
Area under the line
What effect do forces have? Give units
They change speed, shape or direction of a body. (Newtons /N)
What is friction? Give an example
A force between two or more surfaces which impedes motion and results in heating. An example is air resistance
What does Newton’s first law state?
An object has constant velocity unless acted on by a resultant force. (objects at rest will stay at rest and objects in motion will stay in motion unless acted upon by an outside force)
What does Newton’s second law state?
Force is mass x acceleration
Acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass.
What does Newton’s third law state?
Define inertia
The tendency for an object to resist changes in its velocity
