Forces Flashcards
What are forces?
Forces are pushes and pulls that occur when objects interact.
Can you see a force?
We can see the effects of the forces but not the forces themselves.
What are contact forces?
Forces that only occur when objects are touching.
What are some contact forces?
-Friction
-normal contact force
-air resistance
-upthrust
What are non-contact forces?
Forces that can occur over a distance.
What are some non-contact forces?
-weight
-magnetic
-electrostatic
How are forces represented on diagrams?
Forces are represented on diagrams by using a scaled arrow.
What does a dot represent in a free body diagram?
The object
How is the object represented in a free body diagram?
A dot
Which direction do the arrows point in a force diagram?
The arrows should point in the direction of the force
What does it mean when forces are balanced?
When forces acting in opposite directions are the same size we say the forces are balanced
What happens to a stationary object when the forces on it are balanced?
It remains stationary.
What happens to a moving object when the forces on it are balanced?
It moves with constant speed.
What does it mean when forces are unbalanced?
When forces acting in opposite directions are NOT the same size we say the forces are unbalanced
What happens when the forces on an object are unbalanced?
An object can speed up, slow down or change direction.
When will an object float?
If the upthrust can equal the weight.
When will an object sink?
When the weight is greater than the upthrust
If the overall density of an object is greater than that of the liquid it will _____
sink
How can you change if an object floats or sinks?
Changing the shape of the object (to include air) or the temperature/density of the liquid.
What else can you call air and water resistance?
Drag force
Drag force is in the ________ direction to the movement
Opposite
How can you increase the drag force of an object?
-Larger surface area
-moving faster
-moving through a more viscous liquid
How can you decrease the drag force of an object?
streamline the object
How does a parachute work?
A parachutist will accelerate towards the ground when their weight is bigger than air resistance (unbalanced). When air resistance is the same size as weight it will move at a constant speed (balanced). Opening a parachute increases air resistance and it slows the parachutist down (unbalanced).
What is mass
The amount of matter an object is made from.
How do you measure mass
In kilograms, kg
What is weight
the force when gravity is acting on a mass.
How is weight measured?
In Newtons, N
What is the word equation for weight?
weight = mass x gravitational field strength
Is weight variable or constant
Weight varies with gravitational field strength.
Is mass variable or constant
Mass will always be constant
All objects with mass have a…
gravitational pull
Objects with more mass (like planets) have a greater or lesser gravitational pull
greater
Is the gravitational pull stronger nearer or further from the object?
Nearer (on Earth’s surface rather than orbiting).
Friction occurs when…
One surface moves along another
A rough surface will cause a _______ friction force than a smooth surface.
larger
Is friction the same or opposite direction to movement?
Opposite direction
How can you reduce friction?
By using lubrication such as oil.
How is friction useful?
It stops us falling over.
How is friction unhelpful?
It causes surfaces to wear away and heat up
How does a Newton meter work?
A pulling force like weight will stretch a spring
Forces can change the shape of an object by…
Stretching (extending) or compressing (squashing)
Ir order to get reliable results, only one _______ should be changed during an experiment
variable
A spring will stretch proportionally to the force applied. This means that if the force is doubled, the length it extends…
doubles.
