3. Dynamics Flashcards
What is the definition of speed?
Speed is the distance travelled per unit of time
What is the speed, distance and time formula?
d = vt
What is the average speed formula?
-
v = d / t
What is the definition of instantaneous speed?
The speed of an object at any given moment
What device can be used to measure instantaneous speed?
Police can measure instantaneous speed using a radar gun or speed camera
Which formula can be used to find instantaneous speed?
v (isnt) = d (length of vehicle) / t (takes to pass)
What are vectors and scalars?
A vector represents direction and magnitude
A scalar represents just magnitude
How are vector quantities portrayed?
The unit symbol is in bold, but when handwriting put an arrow over the units
Name some vectors
Velocity Force Displacement Acceleration Weight
Name some scalars
Speed Distance Mass Time Energy
What is the difference between distance and displacement?
Distance is the total distance travelled, whereas displacement is the distance from the start point to the end point in a straight line
Distance and Displacement
E.g A man travels 4km East, then 2km South and then 4km West (draw diagram)
What distance has the man travelled?
What is the displacement of the man?
d = 4km + 2km + 4km
= 10km
s = 2km SOUTH / 2km on a bearing of 180•
What is the difference between velocity and speed?
Speed is only a scalar, whereas velocity is a vector, which means when using velocity magnitude AND direction have to be used
What is the velocity equation?
s = vt
How do you work out the direction for velocity?
It will be the same as the displacements direction
E.g. Using trigonometry/ scale diagram
What is the definition of acceleration?
Acceleration is the rate at which an object changes its velocity
What is the acceleration formula?
a = v - u / t
OR
a = delta v / t
Why does a graph about acceleration level out as the track gets higher?
It reaches a maximum velocity
What will a velocity / time graph look like when it is describing:
Acceleration?
Deceleration?
Constant speed?
Acceleration = the line sloping up
Deceleration = the line sloping down
Constant speed = the line is horizontal
What does the gradient of the line represent?
The gradient of the line is equal to the acceleration
What is the gradient formula?
m = vertical / horizontal
How do you work out the displacement of an object using a velocity / time graph?
The area under the graph is equal to the displacement
