Motion and it's Measurements Flashcards
What is speed
How fast an object is moving, regardless of direction
What is displacement
How far an object has travelled from its starting point in a given direction
What is velocity
Rate of change of displacement
What is acceleration
Rate of change of velocity
What is the equation for velocity
v = Δs/Δt
Velocity (m/s) = Δ Displacement (m)/ Δ Time (s)
What is the equation for acceleration
a = Δv/Δt
Acceleration (m/s^2) = ΔVelocity /ΔTime
What is instantaneous velocity
The velocity of an object at a specific point in time
It can be found from a displacement-time graph by drawing a tangent to the graph at the specific time and calculating the gradient
What is average velocity
The velocity of an object over a specified time frame
It can be found by dividing the final displacement by the time taken
Describe a Distance-Time Graph
What is uniform acceleration
When the acceleration of an object is constant
Describe uniform and non-uniform acceleration on an acceleration-time graph and the area under the graph
Describe a Velocity-Time Graph
What are the 4 SUVAT questions
- v = u + at
- s = (u + v) / 2 x t
- s = ut + ½ at^2
- v^2 = u^2 + 2as
When can SUVAT equations be used
When object is moving at uniform acceleration
How do you approach projectile motion questions
- Remember horizontal and vertical motion can be evaluated separately using the SUVAT equations
- Remember in horizontal acceleration = 0
- Remember in vertical initial velocity = 0 (If fired horizontally)
How do you approach projectile motion questions when an object is projected at an angle
- Resolve the velocity into horizontal and vertical components
- Evaluated the horizontal and vertical components separately using the SUVAT equations
What is a free fall
When an object experiences an acceleration due to gravity
What is friction
A force which opposes the motion of an object (known as drag in fluids)
Which energy transfers does friction result in
Friction converts kinetic energy into other forms such as heat and sound
What happens to air resistance when the speed of an object increases
Air resistance increases
What is lift
- An upwards force that acts on an object moving through a fluid
- Acts perpendicular to the direction of fluid flow
When is lift caused
When an object in a fluid causes the fluid flowing over it to change direction
When is terminal speed achieved
- Occurs when the frictional forces acting on an object and driving forces are equal
- Therefore there is no resultant force and so no acceleration
- So the object travels at a constant speed
Describe how a moving object reaches terminal speed
- Constant driving force (e.g gravity) causes acceleration.
- As speed increases, the frictional force increases. This reduces the resultant force
- Therefore reducing the acceleration
- Eventually, the frictional force equals the driving force and terminal speed is achieved
Describe the effect of air resistance on the trajectory of a projectile
Without air resistance it will travel further
What is needed for a moving object to reach a terminal velocity
- Driving force that stays constant
- Frictional force that increases with speed
What factors increase a moving object’s terminal speed
- Increase the driving force (e.g. bigger engine)
- Reduce the frictional force (e.g. more streamlined object)
