Forces (Seneca) Flashcards
Scalar quantities only have a …
magnitude (size).
Speed is a ——— quantity.
scalar
Scalar quantities, like speed, do not have a …
direction
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.
The average speed (measured in metres per second, m/s) is equal to the …
distance travelled (metres, m) divided by the time taken (seconds, s).
Average speed =
total distance / total time
If two people stand back-to-back and walk away from each other at the same speed, but in opposite directions, their speeds are the same but …
one will have a positive velocity and the other will have a negative velocity.
Velocity describes an object’s ———- as well as its speed.
direction
————- theorem is used to work out the resultant force.
Pythagoras’
Acceleration =
Change in velocity / time taken
Displacement is the …
distance an object moves in a straight line from a starting point to a finishing point.
Displacement is a ——— quantity.
vector
Distance is a ———- quantity.
scalar
Distance is …
how far an object moves.
A force is a …
push or a pull that acts on an object when it interacts with another object.
All forces between objects are either:
- Contact forces
- Non-contact forces
Contact forces happen when …
two objects are physically touching.
———- are all examples of contact forces.
Friction, air resistance, tension and normal contact force
Non-contact forces happen when …
objects are separated (not touching).
———— are all examples of non-contact forces.
Gravitational force, electrostatic force and magnetic force
Tension is …
the pulling force that a string or cable exerts (creates) when something or someone pulls on it.
When you push on a table, your hand doesn’t move through it.
This is because …
the normal contact force from the table pushes equally on your hand.
Air resistance comes about when …
an object moves through the air and collides with (hits) air molecules.
Friction comes about whenever …
two surfaces are touching and try to move against each other.
Tiny bumps in the surface ——————. This creates a frictional force that opposes their motion.
interlock (overlap or fit together)
An interaction pair is a …
set of 2 forces that are equal and opposite, acting on 2 interacting objects.
Distance-time graphs have distance on the 1. and time on the 2.
- y-axis
- x-axis.
On a distance-time graph, motion (movement) at a constant speed is shown by a …
straight line.
On a distance-time graph, If the line is horizontal, then the object is …
stationary
On a distance-time graph, If an object is accelerating, we can measure its speed by …
drawing a tangent and measuring the gradient of the distance-time graph at that point.
Speed-time graphs have speed on the 1. and time on the 2.
- y-axis
- x-axis
Velocity-time graphs would simply have ———- on the y-axis instead of speed.
velocity
If an object slows down, its graph will have a ——— gradient.
negative
The area under a velocity-time graph is equal to the …
distance travelled by an object.
On a distance-time graph, if the object moves faster, the gradient becomes …
steeper
On a speed-time graph, A curved line shows that an object is …
accelerating or decelerating at a rate that is not constant.
Velocity =
Displacement/ time
If a velocity-time graph consists of one diagonal line in the downwards direction, what statements about the motion are true?
- the object is decelerating at a constant rate
- the object is travelling at a non-constant velocity
Objects that move in a circular path at a constant speed have ——— acceleration as their direction is constantly changing.
positive
The mass of an object is a measure of …
the amount of matter it contains.
The mass of an object is …
constant
An object’s mass is also a measure of …
how difficult it is to change the object’s motion.
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 ——— inertia than an object with a lower mass.
more
It is difficult to move an object with a ———— , and once it is moving, the object’s motion is hard to stop.
high mass (and high inertia)
What is the name of the measure of how difficult it is to change an object’s motion?
Inertia
Although the mass of an object is spread out across its body, it is possible to find a …
single point where all of the mass appears to be.
Although the mass of an object is spread out across its body, it is possible to find a single point where all of the mass appears to be. This point is called …
the object’s centre of mass.
If an object is hung from a string, it will hang with its centre of mass directly …
below the point that it is hung from.
The centre of mass is the …
point through which an object’s weight appears to act.
An object will fall over if its …
centre of mass is outside its base.
An object will fall off a surface if its …
centre of mass isn’t over the surface.
A force may cause a mass to …
accelerate
A force may cause a mass to accelerate. This acceleration can be a …
change in speed, a change in direction or a change in both speed and direction.
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 — is acting on a object.
resultant force
Resultant force (F) =
mass (m) x acceleration (a)
What is Newton’s second law?
Resultant force (F) = mass (m) x acceleration (a)
The acceleration can be calculated with the following equation:
Resultant force (F) = mass (m) x acceleration (a)
If an object is stationary (not moving) and there is no resultant force acting on it, it will …
stay stationary.
When a vehicle is travelling at a steady speed, the resistive forces (such as friction and air resistance) are …
balancing the driving force.
When a vehicle is travelling at a steady speed, the resistive forces (such as friction and air resistance) are balancing the driving force.
When there are balanced forces, there is …
no resultant force.
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.
A free body force diagram is a …
diagram showing the forces acting on an object.
A free body force diagram is a diagram showing the forces acting on an object. These are shown as …
vectors
We can use free body diagrams to work out the resultant force when more than one force is acting on an object. We can also use the diagrams to see if an object is in …
equilibrium
We can use free body diagrams to work out the resultant force when more than one force is acting on an object. We can also use the diagrams to see if an object is in equilibrium. If the resultant force is ——- , we say the object is in equilibrium.
zero
What is the term used for an object that has no resultant forces on it?
Equilibrium
We can split a force into —————— We can use grid lines to find the size of these forces.
horizontal and vertical parts.
We can stretch, bend or compress objects by applying forces to them.
For this to happen, there must be …
2 or more forces acting on an object.
We can stretch, bend or compress objects by applying forces to them.
For this to happen, there must be 2 or more forces acting on an object.
If only one force is acting, the object will …
just move in the direction of that force.
Objects can stretch, bend or compress objects by applying forces to them.
For this to happen, there must be 2 or more forces acting on an object.
If only one force is acting, the object will just move in the direction of that force.
Because of this, we can normally only stretch, bend or compress ————- objects.
stationary (still)
Objects can be deformed in 2 ways :
elastically and inelastically.
An elastically deformed object will …
return to its original shape when the force stops.
An inelastically deformed object will …
not return to its original shape when the force stops.
An extension-load graph has the —————- plotted on the y-axis, and the extension of the spring on the x-axis.
force acting on a spring
An extension-load graph has the force acting on a spring plotted on the y-axis, and the ————— on the x-axis.
extension of the spring
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.
Hooke’s Law tells us that the …
Force (measured in newtons, N) is equal to the spring constant (measured in N/m) times the spring extension (measured in metres, m).
What property of a spring does the spring constant represent?
Stiffness