Seneca P5 Flashcards
What is speed
Speed is a scalar quantity.
Scalar quantities only have a magnitude (size).
Scalar quantities, like speed, do not have a direction.
What is Velocity
Velocity describes an object’s direction as well as its speed.
Velocity is a vector quantity because it has a magnitude (or size) and a direction.
What is the speed of an object
The speed of an object is the total distance that an object travels divided by the total time it takes.
What is the formula for acceleration
acceleration (m/s2) = Δv (change in velocity) / t (time taken)
Why do we work out acceleration using velocity
Because velocity is a vector quantity, acceleration is also a vector quantity
Uniform acceleration
v^2 - u^2 = 2as
final velocity squared
minus initial velocity squared
is equal to distance x acceleration x 2
What is the difference between a scalar and a vector
Scalar only has magnitude (size)
Vector has magnitude and direction
Distance
Distance is how far an object moves.
Distance is a scalar quantity.
This is because it contains a magnitude (size) but not a direction.
Displacement
Displacement is the distance an object moves in a straight line from a starting point to a finishing point.
Displacement is a vector quantity.
This is because it contains a magnitude (size) and direction.
What is a force
A force is a push or a pull that acts on an object when it interacts with another object
Contact forces
Contact forces happen when two objects are physically touching.
Friction, air resistance, tension and normal contact force are all examples of contact forces.
Non Contact forces
Non-contact forces happen when objects are separated (not touching).
Gravitational force, electrostatic force and magnetic force are all examples of non-contact forces.
What are examples of contact forces
. Tension
. Friction
. Air resistance
. Normal contact force
What is an interaction
An interaction pair is a set of 2 forces that are equal and opposite, acting on 2 interacting objects.
What is mass
An object’s mass is a measure of the amount of matter that it contains.
Inertia
An object’s mass is also a measure of how difficult it is to change the object’s motion.
This is called inertia.
An object with a high mass has more inertia than an object with a lower mass.
It is difficult to move an object with a high mass (and high inertia), and once it is moving, the object’s motion is hard to stop.
Weight
. Is measured in newtons
. Equals mass multiplied by gravitational field strength
. is the force that acts on an object in a gravitational field
When will an object topple?
When it’s center of mass is located outside it’s base
What is the center of mass
A single point where in an object where all the mass appears to be
Resultant force
The resultant force is the sum of all of the forces acting on an object.
The change in an object’s motion is caused by the resultant force.
If the forces acting on an object are unbalanced (not equal), it means that a resultant force is acting on the object.
This is Newtons 2nd law
What is the equation for resultant force
Resultant force (F) = mass (m) x acceleration (a)
What is Newtons 1st Law
Newton’s 1st Law says that the velocity of an object will only change if a resultant force is acting on the object. This applies to a stationary (still) or moving object.
Stationary (still)
If an object is stationary (not moving) and there is no resultant force acting on it, it will stay stationary.
Moving
If an object is moving and there is no resultant force acting on it, the object will continue moving in the same direction at the same speed.
This means that the object will continue moving at the same velocity.
This also means that the velocity of an object will only change if a resultant force is acting on the object.
What is Newtons third law
Newton’s Third Law says that: whenever 2 objects interact, the forces that they exert on (apply to) each other are equal and opposite.
If one object exerts (applies) a force on another object, then the other object must be exerting (applying) a force back.
If a hand pushes on a table, the table will push back on the hand with an equal force, but in the opposite direction.
We can use ____ body diagrams to work out the resultant force when more than one force is acting on an object.
free
On a free body force diagram, forces are shown as ________.
vectors
If the resultant force on an object is zero, we say the object is in…
equilibirum
At least how many forces must be acting on an object to stretch, bend or compress it?
2
What are the 2 ways an object can be deformed
Elastically
Inelastically
Inelastic deformation
An inelastically deformed object will not return to its original shape when the force stops.
A car is an inelastic object.
After a car has crashed into a tree, it will not return to its original shape.
Elastic deformation
An elastically deformed object will return to its original shape when the force stops.
A spring is an elastic object.
Springs return to their original shape when forces stop acting on them.
Extension Load Graph
An extension-load graph has the force acting on a spring plotted on the y-axis, and the extension of the spring on the x-axis.
For low forces, the graph is a straight line which passes through the origin.
When no force acts on the spring, there is no extension.
As the force on the spring increases, the spring reaches its limit of proportionality.
On the graph shown, this is where the line begins to curve.
What is the limit of proportionality?
The point where hook’s law breaks down
Equation for Hooke’s Law
F = ke
F = Force
k = Constant
e = Extension
Investigating Hook’s Law
Set up the apparatus as above.
First, measure the original length of the spring.
Next, hang different masses on the spring and measure the length of the spring in each case.
Adding masses to the spring increases the downwards force as each mass has weight.
The extension of the spring equals the length with masses minus the original length:
extension of the spring = length of the spring with masses − original length of the spring.
Plot a graph with the extension of the spring on the x-axis and force on the y-axis.
Which law relates the force and extension of a stretched spring?
Hooke’s law
Work done on a spring
When a force stretches a spring or compresses another object, work is done. When this work is done, energy is transferred into an elastic potential energy store.