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Define distance.
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Define distance.
Distance is the total length travelled by an object.
Define displacement.
Displacement is the distance from a reference point in a specified direction.
What is the difference between distance and displacement?
The difference between distance and displacement is:
distance is a scalar quantity, with magnitude but no direction
displacement is a vector quantity, with magnitude and direction.
True or False?
Distance describes how far an object is from where it started and in what direction.
False.
Displacement describes how far an object is from where it started and in what direction.
Define speed.
Speed is the distance an object travels per unit time.
True or False?
Speed is a scalar quantity with magnitude but no direction.
True.
Speed is a scalar quantity with magnitude but no direction.
Define velocity.
Velocity is the rate of change of displacement.
True or False?
Velocity is speed in a given direction.
True.
Velocity is speed in a given direction.
Define instantaneous speed.
Instantaneous speed is the speed of an object at any given point in time.
How is instantaneous velocity found from a displacement-time graph?
To find instantaneous velocity from a displacement-time graph:
draw a tangent to the curve at the required time
calculate the gradient of the tangent
State the equation for average velocity.
The equation for average velocity is or
Where:
= average velocity, measured in metres per second (m s–1)
= change in position, measured in metres (m)
= change in time, measured in seconds (s)
= initial velocity, measured in metres per second (m s–1)
= final velocity, measured in metres per second (m s–1)
Define acceleration.
Acceleration is the rate of change of velocity.
Is acceleration a scalar or vector quantity?
Acceleration is a vector quantity with both magnitude and direction.
State the equation for average acceleration.
The equation for average acceleration is:
Where:
= average acceleration, measured in metres per second squared (m s–2)
= change in velocity, measured in metres per second (m s–1)
= change in time, measured in seconds (s)
State the equation for change in velocity.
The equation for change in velocity is:
Where:
= change in velocity, measured in metres per second (m s–1)
= final velocity, measured in metres per second (m s–1)
= initial velocity, measured in metres per second (m s–1)
Define instantaneous acceleration.
Instantaneous acceleration is the acceleration of an object at a given point in time.
True or False?
If an object changes direction at a constant speed, the object is accelerating.
True.
If an object changes direction at a constant speed, the object is accelerating.
What are the kinematic equations used for?
The kinematic equations are used for describing the motion of objects undergoing uniform acceleration.
State the kinematic equation for calculating final velocity, , from acceleration, , and time, .
The kinematic equation for calculating final velocity from acceleration and time is:
Where:
= final velocity, measured in metres per second (m s–1)
= initial velocity, measured in metres per second (m s–1)
= acceleration, measured in metres per second squared (m s–2)
= time, measured in seconds (s)
State the kinematic equation for calculating displacement, , from acceleration, , and time, .
The kinematic equation for calculating displacement from acceleration and time is:
Where:
= displacement, measured in metres (m)
= initial velocity, measured in metres per second (m s–1)
= time, measured in seconds (s)
= acceleration, measured in metres per second squared (m s–2)
State the kinematic equation for calculating displacement, , from initial velocity, , and final velocity, .
The kinematic equation for calculating displacement from initial and final velocity is:
Where:
= displacement, measured in metres (m)
= final velocity, measured in metres per second (m s–1)
= initial velocity, measured in metres per second (m s–1)
= time, measured in seconds (s)
State the kinematic equation for calculating final velocity, , from acceleration, , and displacement, .
The kinematic equation for calculating final velocity from acceleration and displacement is:
Where:
= final velocity, measured in metres per second (m s–1)
= initial velocity, measured in metres per second (m s–1)
= acceleration, measured in metres per second squared (m s–2)
= displacement, measured in metres (m)
What does it mean if an object starts from rest?
If an object starts from rest, it means that its initial velocity is zero.
What are the three types of motion graph?
The three types of motion graphs are:
displacement-time
velocity-time
acceleration-time
What does the gradient of a displacement-time graph represent?
The gradient of a displacement-time graph represents the velocity of the object.
True or False?
The intercept of a displacement-time graph is equal to the initial displacement.
True.
The intercept of a displacement-time graph is equal to the initial displacement.
True or False?
The area under a displacement-time graph is equal to the distance travelled.
False.
The area under a velocity-time graph is equal to the distance travelled. The area under a distance-time graph is meaningless.
What does the gradient of a velocity-time graph represent?
The gradient of a velocity-time graph represents the acceleration of the object.
True or False?
The intercept of a velocity-time graph is equal to the initial displacement.
False.
The intercept of a velocity-time graph is equal to the initial velocity.
True or False?
The area under a velocity-time graph is equal to the displacement.
True.
The area under a velocity-time graph is equal to the displacement.
What does the gradient of an acceleration-time graph represent?
The gradient of an acceleration-time graph is meaningless.
True or False?
The intercept of an acceleration-time graph is equal to the initial acceleration.
True.
The intercept of an acceleration-time graph is equal to the initial acceleration.
True or False?
The area under an acceleration-time graph is equal to the acceleration.
False.
The area under an acceleration-time graph is equal to the change in velocity.
What is a projectile?
A projectile is a particle that moves freely under gravity in a two-dimensional plane.
Define the time of flight of a projectile.
The time of flight of a projectile is the total time it is in the air.
Define the range of a projectile.
The range of a projectile is the horizontal distance it travels.
Define the maximum height attained by a projectile.
The maximum height attained by a projectile is the height at which it is momentarily at rest, where the vertical velocity component equals zero.
True or False?
The vertical velocity component of an object in projectile motion at maximum height is zero.
True.
The vertical velocity component of the velocity of an object in projectile motion is zero at maximum height.
What is the equation for the vertical component of the velocity of an object in projectile motion.
The equation for the vertical component of the velocity of an object in projectile motion is:
Where:
= vertical velocity component, measured in metres per second (m s-1)
= resultant velocity of the projectile, measured in metres per second (m s-1)
= angle of the projectile to the horizontal, measured in degrees ()
What is the equation for the horizontal component of the velocity of an object in projectile motion?
The equation for the horizontal component of the velocity of an object in projectile motion is:
Where:
= horizontal component of velocity, measured in metres per second (m s-1)
= resultant velocity of the projectile, measured in metres per second (m s-1)
= angle of the projectile to the horizontal, measured in degrees ()
How do you calculate the horizontal distance, , travelled by an object in projectile motion?
The horizontal distance is calculated using:
Where:
= initial horizontal velocity (m s-1)
= time of flight (s)
What is the vertical component of acceleration of an object in projectile motion?
The vertical component of acceleration of a projectile is the acceleration due to gravity
when moving vertically upwards: = -9.8 m s−2
when moving vertically downwards: = +9.8 m s−2
Which set of equations are used to evaluate the horizontal and vertical components of projectile motion?
The kinematic equations are used to evaluate horizontal and vertical components of projectile motion.
Define fluid resistance.
Fluid resistance is a frictional force that opposes the motion of an object moving through a fluid.
Define the term fluid.
A fluid is a gas or a liquid. The particles in a fluid are free to move around.
True or False?
Fluid resistance is the same as viscous drag.
True.
Fluid resistance is another name for viscous drag.
True or False?
Frictional forces always act to oppose the motion of the object.
True.
Frictional forces always act to oppose the motion of the object.
True or False?
Frictional forces never transfer energy away from the moving object.
False.
Frictional forces always transfer energy away from the moving object.
True or False?
Fluid resistance increases as the speed of the object increases.
True.
Fluid resistance increases as the speed of the object increases.
Name the factors affected by fluid resistance in projectile motion.
The factors affected by fluid resistance in projectile motion are:
time of flight
horizontal velocity
horizontal acceleration
range
shape of trajectory
True or False?
Air resistance decreases the horizontal component of the velocity of a projectile so both its range and maximum height will decrease compared to an identical situation with no air resistance.
True.
Air resistance decreases the horizontal component of the velocity of a projectile, so both its range and maximum height will decrease compared to an identical situation with no air resistance (like a vacuum).
True or False?
Air resistance increases the time of flight of a projectile.
False.
Air resistance decreases the time of flight of a projectile.
True or False?
Air resistance changes the shape of the trajectory of a projectile.
True.
Air resistance changes the shape of the trajectory of a projectile; it is no longer a parabola, and its path is steeper on the way down than it is on the way up.
True or False?
For an object in free fall in a vacuum, the only force acting on it is weight.
True.
For an object in free fall in a vacuum, the only force acting on it is weight.
In a vacuum, there are no particles, so there are no drag forces to oppose the motion.
True or False?
For an object in free fall, viscous drag increases as the object accelerates.
True.
For an object in free fall, viscous drag increases as the object accelerates.
Explain how an object in free fall reaches terminal speed.
An object in free fall reaches terminal speed as follows:
initially, weight > viscous drag
resultant force acts downward
object accelerates
viscous drag force increases with speed
eventually viscous drag = weight
resultant force = zero
object no longer accelerates
object falls at a constant terminal speed
Explain how a skydiver in free fall at terminal speed achieves a new terminal speed after opening their parachute.
A skydiver in free fall at terminal speed achieves a new terminal speed after opening their parachute as follows:
viscous drag increases when the parachute opens
viscous drag > weight
resultant force acts upward
object decelerates
viscous drag decreases as speed decreases
eventually viscous drag = weight
resultant force = zero
object no longer accelerates
object falls at a new slower terminal speed
True or False?
When a skydiver deploys a parachute, their direction of motion changes, and they accelerate upward.
False.
When a skydiver deploys a parachute, the direction of the resultant force changes, and they decelerate while still falling downward. Their direction of motion does not change.