Chapter 3 Motion Flashcards
How do you calculate average speed?
Average Speed = Distance travelled / time taken
How is a distance time graph plotted and what does it show?
Distance is on y axis
Time is on x axis
The gradient shows speed
How is constant speed and a stationary object shown on a distance time graph?
Constant Speed - A straight sloping line
Stationary Object - A horizontal straight line
What is instantaneous speed?
The speed of car over a very short interval of time
How is instantaneous speed found on a distance time graph?
By drawing a tangent and determining its gradient
How is average velocity calculated?
Average velocity = Change in displacement / time taken
How is a displacement time graph plotted and what does it show?
Displacement is on y axis
Time is on x axis
Velocity is shown by the gradient or by drawing a tangent to the gradient
What is acceleration?
The rate of change of velocity
How is acceleration calculated?
Change in velocity / Change in time
How is a velocity time graph plotted and what does it show?
Velocity is y axis
Time is x axis
Gradient shows acceleration
Area under graph shows displacement
What do these show on a velocity time graph?
a straight line of positive gradient
a straight line of zero gradient
a straight line of constant negative gradient
a curve with changing gradient
Straight positive line - Constant acceleration
Straight 0 gradient line - Constant velocity or 0 acceleration
Straight negative line - Constant deceleration
Curve - Acceleration is changing
How do work out displacement from linear and non-linear velocity time graphs?
Linear - Split into shapes and find area
Non-Linear - Count boxes
What are the suvat equations?
v = u+at v² = u² + 2as s = ut + ½at² s = vt - ½at² s = ½(u+v)t
What does SUVAT stand for?
S = Displacement U = Initial Velocity V = Final Velocity A = Acceleration T = Time
What is stopping distance?
The total distance travelled from when the driver sees the reason to stop to when the vehicle stops
Thinking Distance + Braking Distance
What is thinking distance?
Distance travelled between the moment when you first see a reason to stop, to the moment when you use the brake
What is braking distance?
Distance travelled from the time the brake is applied until the vehicle stops
What is the equation for thinking distance?
Thinking distance = Speed x reaction time
What is free fall and what is the acceleration of free fall denoted by?
When an object is accelerating under gravity with no other force acting on it
denoted by g
What is the value of g?
9.81ms–2
What is a light gate?
Two light beams, one above the other connected to a timer so that when an object interrupts the light, the timer starts and when it passes the second one the timer stops.
What happens when one ball is dropped vertically and one ball is thrown horizontally from the same height at the same time?
Both fall at the same rate as the vertical and horizontal components are independent of each other?
Assuming no air resistance, what happens to the vertical velocity, vertical displacement/time of flight and horizontal velocity of a ball thrown horizontally?
Vertical velocity - Changes due to acceleration of free fall
Vertical displacement and time of flight - Can be calculated using suvat
Horizontal Velocity - Remains constant
How do you calculate the magnitude of the actual acceleration in projectile motion?
Use pythagoras with the vertical and horizontal components
How do you work out the horizontal and vertical component of a projectile fired at angle θ with initial velocity v?
Horizontal Component = vcosθ
Vertical Component = vsinθ
