YEAR 9 - Topic 4 - Movement, terminal velocity, newtons 1st and 2nd law and Forces??? Flashcards
What types of forces are there?
- weight
- reaction
- drag
- upthrust
- electrostatic
- magnetic
- tension
- thrust
What are examples of non contact forces?
- weight
- electrostatic
- magnetic
What are examples of contact forces?
- reaction
- drag
- upthrust
- tension
- thrust
What can a force do to an object?
Change it’s:
- speed
- direction
- shape
What does this force mean?
Weight
Weight is the force due to mass being in a gravitational field.
What does this force mean?
Reaction
Reaction is the force of a surface that it applies back up when a weight presses down on it.
What does this force mean?
Drag
Drag is both friction and air resistance. It occurs when two surfaces rub together, this force acts in the opposite direction to the motion and tries to slow the object down.
What does this force mean?
Upthrust
Upthrust is often called lift. It refers to the upwards force in liquids (like a boat floating) and in gases (like aeroplane wings).
What does this force mean?
Electrostatic
Electrostatic is the force betweeen two electrically charged objects/ particles.
What does this force mean?
Magnetic
Magnetic is the force between two magnets.
What does this force mean?
Tension
Tension is the force in a rope or cable.
What does this force mean?
Thrust
Thrust is the forward force in a rocket to speed it up.
What is resultant force?
Resultant force is the overall effect of all the forces acting on an object. It takes into account direction and size.
What is Newton’s 1st law?
Newton’s first law is the theory that if there is no resultant force (all the forces are balanced), then there is no change in speed. This means an object either stays still or moves at a steady speed.
What is Newton’s 2nd law?
Newton’s 2nd law is the theory that if forces are unbalanced, and there is a resultant force, then the object will either accelerate or decelerate. This means that there will be a change in speed.
What is the acceleration equation?
Force = mass X acceleration
/\
/ Fr \
/-——\
/ m X a \
—————How do you remember the acceleration triangle?
My Funny Aunt
What is acceleration?
Acceleration is the change in velocity every second.
What is the difference between mass and weight?
Mass is the amount of matter in a substance, linked to the number of particles. Weight is the force on mass due to being in a gravitational field.
What is mass?
Mass is the amount of matter there is in a substance linked to the amount of particles there are.
What is weight?
Weight is the force on a mass due to a gravitational field.
How do you work out drag?
Drag = weight - resultant force
Which of the two can change?
Mass and weight
Weight scan change as it depends on the strength of the gravity.
What is gravity strength on earth?
10N/kg
What is the gravity strength on the moon?
1.62 N/Kg
What is the mass, weight and GFS equation?
Weight = mass X GFS
/ \
/ w \
/———\
/ m X GFS \
—————-What factors affect the size of friction?
- the type of surface
- mass of the object
How do you work out the overall stopping distance?
Thinking distance + braking distance
How do you work out thinking distance?
Thinking distance = speed X reaction time
What is the average reaction time?
0.6 seconds
What can slow down your reaction time?
- alcohol/drugs
- Fatigue
- hazard perception ability
- vision issues
What is the thinking distance?
Thinking distance is the distance travelled while reacting to a stimulus, until the breaks are used.
What is breaking distance?
Breaking distance is the distance travelled by a vehicle whilst braking.
What factors affect braking distance?
- road surface
- weather conditions
- vehicle mass
- speed of vehicle
How do you work out braking distance?
Mu2
——
2Fr
Mass X initial speed squared
————————————-
2 X resultant force
How does thinking distance increase?
Thinking distance increases linearly
How does braking distance increase?
Braking distance increases squared.
What does air resistance depend on?
Air resistance depends on surface area and speed.
Do skydivers ever go up?
NO! (Other than in the plane)
What is terminal velocity?
A terminal velocity is where the air resistance balances out the velocity. This means that the skydiver doesn’t accelerate any more until the surface area changes.
