Chapter 3: Motion Flashcards
What is kinematics?
Kinematics is the science of describing the motion of objects
What is velocity? What is the equation?
Velocity is the rate of change of displacement
Average Velocity = Displacement/Time
What is speed on a distance-time graph?
Speed is the gradient
What is acceleration?
Acceleration is the positive rate of change of velocity. On a displacement-time graph, it appears as the gradient becoming more positive
What is deceleration?
Deceleration is the negative rate of change of velocity. On a displacement-time graph, it appears as the gradient becoming more negative
What is distance on a speed-time graph?
Area underneath the graph
What is the equation for velocity?
Final velocity - Initial Velocity /// Time
What is the SUVAT equation without ‘s’?
v = u + at
What is the SUVAT equation without ‘v’?
s = ut + 1/2*(at2)
What is the SUVAT equation without ‘a’?
s = 1/2(u+v)t
What is the SUVAT equation without ‘t’?
v2 - u2 = 2as
What is the SUVAT equation without ‘u’?
s = vt - 1/2*(at2)
What does constant thrust result in?
Constant thrust is a constant force with a constant acceleration
What is acceleration upwards and downwards on earth equal to?
-9.81m/s2
9.81m/s2
Do objects dropped and thrown reach the ground at the same time?
Yes. The vertical components become equal in both as the acceleration from gravity is equal
What is the horizontal property of projected objects?
The horizontal component remains constant
What is the vertical property of projected objects?
The vertical component of a projected object increases each time as gravity accelerates the vertical component
What is thinking distance?
Thinking distance is the distance the car travels in the time between the driver noticing the hazard and applying the brakes
What is braking distance?
Braking distance is the distance taken to stop once the brakes are applied
What is the equation for stopping distance?
Stopping Distance = Thinking Distance + Braking Distance
What factors affect thinking distance?
Drugs
Alchohol
Speed
People in the car
What factors affect braking distance?
Tyre Tread
Speed
Ice
Road Surface
People in the car
What is the formula for car stopping distance?
s = ut0 + u2 / 2a
t0 is thinking time
What is the relationship between stopping distance and initial velocity?
Distance is directly proportional to u2
How do you estimate instantaneous speed?
Take the gradient of the tangent at a given point on a distance-time graph
How do you estimate instantaneous acceleration?
Take the gradient of the tangent at a given point on a speed-time graph
What are the two forces acting on a body when it falls through air on earth?
Weight
Drag (Air)
When is drag force in free-fall not ignored?
The body’s mass is very small in relation to surface area
A body is falling at a considerable velocity
