Forces Flashcards
What is a vector quantity
Quantity that has a direction and magnitude
What is a scaler quantity
Quantity with only magnitude
What are contact forces
When two objects have to be touching for the force act e.g. friction, a resistance, tension, normal contact force
What are noncontact forces
When the objects do not need to be touching for the forced act e.g. magnetic force, gravitational force, electrostatic force
What is the difference between weight and mass
Mass is just a matter of stuff on an object where is wait is the force acting on an object due to gravity
What is Newton’s first law
If the resultant force on a stationary object is zero, the object will remain stationary or will carry on moving at the same velocity
What are Free body diagram
They show all the forces acting on an object
What Is resultant force
The overall force on a point or object
What is distance
How far on objects move
– it is a scaler quantity and doesn’t involve direction
What is displacement
Displacement is a vector quantity
– it measures distance and direction in a straight line from the object starting point to its finish point
What is speed
Speed is just how fast are going with no direction
What is velocity
velocity is speed given in a direction
What is the equation for distance travelled
Speed (metres/seconds) X time (S)
What are the typical everyday speeds for – walking – running – cycling -car – train – plane
Walking – 1.5 Metres per second running –3 m/s Cycling – 6 m/s Car – 25 m/s train – 30 m/s plane – 250 m/s
What is acceleration
The change in velocity in a set amount of time
What is Newton’s second law
Acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object
What is drag
The resistance you get in a fluid
What is terminal velocity
This is when the resultant force is zero
– the frictional force is equal to the accelerating force
What is friction
A force that acts in the opposite direction of movement
What happens To drag as speed increases
Drag increases as speed increases
Why must a car at a steady speed have a driving force
The driving force is cancelled out by the drag
What affects terminal velocity
The less streamline the object is, the lower it’s terminal velocity (Object of large surface areas tend to have lower terminal velocity’s )
-This is because there is more a resistance acting on the object surface area
Acceleration is proportional to the resultant force
Resultant force = mass X exhilaration
What is Newton’s third law
When two objects interact, the forces they exert on each other are equal and opposite
What ideas do Newton’s third law give
If you push something, it will push against you with the same force and as soon as you stop pushing so does it
– e.g. two skaters of different
mass: when they push off each other they feel opposite force In opposite directions and therefore Excelerator in different directions however as one has a smaller mass they will accelerate more
What is thinking distance
Distance the car travels while different driver reacts to a hazard and starts to apply the brakes
What Is breaking distance
The distance the car travels once the brakes have been applied and it comes to rest
Factors can affect your thinking distance
Speed – the fast you’re going to further your travel during the time you take to react
– your reaction time – the longer your reaction time the lobby of thinking distance
– tiredness
– distraction
– drunkenness
What are the factors that can affect your braking distance
Your speed – takes longer to break
– the weather or road surface-If it is wet or icy there is less group between the vehicles ties on the road
– conditions of tiredness –
– how good your brakes are – if they are 40 or worn they won’t be able to apply the force needed
Where is the energy transfer when the car breaks
When a force is applied to the breaks of the vehicle, work done by the frictional force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases
How do you check for reaction time
Ruler drop test
What is the ruler drop test
One – sit with your arm resting on the edge of the table and get someone to hold a ruler so it hangs between your thumb and forefinger are lined with zero
Two-Without giving any warning the person holding the ruler to drop it and the other person should catch as quickly as possible
Three – the measurement on the ruler is the point where is court
Four – the longer the distance the longer reaction time
Five –
What is the principle of conservation of momentum
Momentum is conserved in any collision or explosion provided no external factors or forces acts on the colliding or exploding bodies
What happens to the extinction when the force is too large
The extension will reach its limit of proportionality
Ching, compressing or bending transfers energy
When you apply a force on object you may cause it to stretch, compress or bend
-If an object has been elastically deformed it can go back to the original shape and length after it has been relieved of the force
– if an object has been inelastically deformed it can’t return to its original shape and length
– work is done when the force stretches or comprises of an object
