3 - Motion Flashcards
What is average speed?
The average speed of an object over the entire course of its journey.
What is instantaneous speed?
The speed of an object over a very short interval of time.
What does the gradient of a straight distance time graph represent?
The average speed.
How do you find the instantaneous speed at a certain time from a distance time graph?
Draw a tangent to the line at that time and find the gradient of the tangent.
How do you find the top instantaneous speed from a distance time graph?
Draw a tangent at the steepest point of the graph and find the gradient.
Define acceleration.
The rate of change in velocity.
What is the difference between speed and velocity?
Speed is a scalar and velocity is a vector.
What is acceleration, a scalar or a vector?
Vector (determined from velocity)
What does the gradient of a velocity time graph represent?
Acceleration
What are all of the suvat equations?
v =u + at
s = ut + 1/2at^2
s = (v+u)/2 x t
v^2 = u^ + at
What is thinking distance?
The distance traveled in the time between the driver realising that they have to stop, and starting to brake.
What is braking distance?
The distance travelled in the time from when the brake is pressed to when the vehicle stops.
What is stopping distance?
Thinking distance + breaking distance
How do you calculate thinking distance?
speed x reaction time
What factors affect thinking distance?
- Tiredness
- Alcohol/depressants
- Distractions
- Speed of the car
- Age
- Stimulants
What factors affect stopping distance?
- Tyre condition
- Road condition
- Weather
- Brake condition
- Mass of the car
- Speed of the car
What do all objects with a mass exert?
A gravitational pull on other massive objects around them.
What does massive mean?
An object as a mass.
What is gravitational field strength?
The acceleration that an object experiences due to gravity.
What is the gravitational field strength close to the surface of the earth?
9.81m/s
What must you always remember when calculating projectile motion?
Horizontal and vertical projectile motions are independent of each other.
What steps must you follow when calculating projectile motion?
- Sketch and label everything
- Split magnitude of velocity into vertical and horizontal components using trigonometry
- Work out missing suvat values for each component
What is the relationship between braking distance and velocity?
Distance ∝ velocity^2
What is the relationship between braking distance and mass?
Distance ∝ mass
