Speed and Acceleration Flashcards
What is a scalar quantity?
A quantity that only has magnitude (size).
Give five examples of scalar quantities.
Mass, time, distance, volume, density.
What is a vector quantity?
A quantity that has both magnitude and direction.
Give four examples of vector quantities.
Force, acceleration, velocity, displacement.
What is the difference between distance and displacement?
- Distance: The total path traveled between two points.
- Displacement: The shortest straight-line distance between two points.
What is the formula for average speed?
Averagespeed = Totaltime / Totaldistance
β
How can you find average speed from a graph?
Use the gradient:
(π¦2β π¦1) / (π₯2 β π₯1)
(riseoverrun)
What is maximum speed?
The highest speed recorded, found by identifying the steepest straight line on a graph.
What is instantaneous speed?
Speed at a specific moment in time.
How do you find instantaneous speed from a graph?
Draw a tangent to the curve and measure its gradient.
What is the formula for acceleration?
a = (vβu) / t
where:
* a = acceleration
* π£ = final velocity
* π’ = initial velocity
* π‘ = time
What is increasing acceleration? Give an example.
Acceleration that increases at an increasing rate.
* Example: 1π/π , 3π/π , 7π/π (+2,+4)
What is decreasing acceleration? Give an example.
Acceleration that slows down over time.
- Example: 1π/π , 5 π/π , 7 π/π (+4, +2)
- Occurs in cars reaching terminal velocity.
What is constant uniform acceleration? Give an example.
Acceleration that stays the same over time.
* Example: 1π/π , 3 π/π , 5 π/π (+2, +2).
What is constant deceleration? Give an example.
Velocity decreases at a constant rate.
* Example: 10 π/π , 7 π/π , 4 π/π (β3, β3)
What does a horizontal line on a speed-time graph mean?
Constant velocity (speed stays the same over time).
How do you calculate distance from a speed-time graph?
Find the area under the graph.
What formula do you use for a triangleβs area?
1/2 Γ Base Γ Height
What formula do you use for a rectangleβs area?
Length Γ Width
What formula do you use for a trapeziumβs area?
1/2 Γ (Base 1+ Base 2) Γ Height
How do you estimate the area under a curved speed-time graph?
- Find the midpoint of the curve.
- Divide the area into two shapes.
- Approximate each area and sum them.
What is free-fall motion?
Motion under the effect of gravity only.
What is the acceleration due to gravity on Earth?
9.8π/π ^2
(use 10π/π ^2
in exams).
What happens to speed and acceleration in free fall?
- Speed increases as the object falls.
- Acceleration remains constant at 9.8 π/π ^2
Does mass affect free fall?
No, all objects fall at the same rate when air resistance is ignored.
What does a straight, diagonal line on a distance-time graph mean?
Constant speed.
What does a horizontal line on a speed-time graph mean?
Constant velocity (no acceleration).
What does a curve on a distance-time graph mean?
Changing speed (acceleration or deceleration).
What does a downward-sloping speed-time graph mean?
Deceleration (slowing down).
What happens when an acceleration-time graph is a horizontal line above zero?
Constant acceleration.
What information can you extract from a velocityβtime graph?
- The gradient (slope) of a velocityβtime graph gives the acceleration
- The area under the curve represents the displacement of the object.
How do you determine instantaneous velocity using a graph?
Instantaneous velocity is found by drawing a tangent at the point of interest on a velocityβtime graph; the gradient of this tangent line represents the instantaneous velocity.
What are the basic kinematic equations that are useful in motion analysis?
Common equations include:
* π£ = π’ + ππ‘
* π = π’π‘ + (1/2)ππ‘^2
* π£^2 = π’^2 + 2ππ
where π’ is initial velocity, π£ is final velocity, π is acceleration, π is displacement, and π‘ is time.
Why is vector addition important when dealing with velocity and displacement?
Because velocity and displacement are vector quantities (having both magnitude and direction), using vector addition helps in accurately determining the overall effect when combining movements in different directions.
