Forces Flashcards
Describe scalar quantities ?
Scalar quantity’s have magnitude (amount) only
Distance is taken into account
Describe vector quantity’s ?
Vectors quantities have magnitude (amount) and direction
Displacement is taken into account not distance due to direction
What is a contact force simple explanation ?
The objects are physically touching
What is non-contact force simple explanation ?
The objects do not need to touch are physically separated
Example of scalar quantity’s ?
Speed, energy, power, pressure, temperature
Examples of vector quantities ?
Velocity, drag, thrust, force, momentum and acceleration
Examples of non contact forces ?
Magnetic, electrostatic and gravitational
Examples of contact forces ?
Weights, friction, air resistance and normal contact
What is resultant force ?
The sum of all forces acting on a body
It’s decides the speed and direction of the body
Describe force (3 actions) ?
Force is a push or a pull on an object that causes it to
1) change speed
2) change direction
3) change shape
Why is friction a necessary evil ?
Example :
Friction can cause wear of tires but without friction the car will slide
What does the weight of a force depend on (gravitational field strength) ?
The weight of an object depends on its gravitational field strength at the point where the object is.
What way can you measure weight ?
Newtonmeter
What is net force ?
Forces are balanced (0N)
Body will not move
What are moments ?
The turning affect of force on an object
The shorter the effort from the pivot mean that the more load can be lifted.
Example :
The shorter the stick is on the pivot the more rocks it can lift because more momentum can be gained on smaller effort
Give 3 examples of levers ?
1) scissors
2) spanner
3) bottle opener
What do gears do ?
They transmit the turning effect of force
the bigger the gear means more radius so greater turning affect
What does a low gear do ?
For example on a bike a low gear moves at a low speed with higher turning affect
What does a high gear do ?
For example on a bike a high gear moves at a fast speed with lower turning affect
What is velocity ?
Speed in a given direction
What is the differences of an object in pressure at different depths of a liquid ?
A submerged object will have a greater pressure on the bottom surface than the top.
(Varies with depth) due to more water molecules
This creates a resultant force upwards called up thrust.
Just like a human the deeper under water we go the more pressure we experience.
How do you calculate an object that moves in a straight line ?
A distance speed time graph
What does Newton’s first law of motion say about motion of an object ?
It says that a resultant force is required to change the motion of an object because if a moving object had no resultant force it would carry on moving with the same velocity
And if a stationary object had no resultant force it would stay stationary
No resultant force means no change
What does Newton’s second law of motion say about motion of an object ?
Newton’s second law says if they’re is a resultant force on an object it will cause it to accelerate
Resultant force = anything but zero
Depending on the original position/movement of the object the result force could cause it to go faster in a certain direction
Or completely stop due to the force in the other way
What is inertia ?
It’s the idea that unless an object is acted on it will not change motion
What does Newton’s third law of motion say about an object ?
When two objects interact the forces they exert on each other are equal and opposite
For example =
If you push a box with 100N the box will have an equal 100N force on you, they would just be acting on opposite directions and depending on the mass of you or the box one would move
What is the stopping distance equal to ?
Stopping distance = thinking distance + braking distance
What is the thinking distance ?
How far the car travels while the driver see’s the object thinks and apples the brakes
What two things affect thinking distance ?
- Speed of vehicle
- Reaction time
Why does speed affect your thinking distance ?
Because the faster your travelling the further you’re travelling
What things affect the reaction time of someone ?
Tiredness
Drinking
Drugs
Distracted
What is the braking distance ?
Distance taken to stop under the force of brakes
What are important factors that affect braking distance ?
Speed of vehicle
Mass of vehicle
Condition Of the brakes
Traction between the car and road
How does pressure affect braking distance ?
The more pressure means the shorter the braking distance will be the longer the braking distance will be less pressure vice versa
What things affect the traction between car and road ?
Wet road
Icy road
Lack of grip on tires
What does the affect of speed have on a graph of stopping distance ?
The faster your travelling the longer it will take you to stop
What is the conservation of momentum principe ?
The total momentum before is = to the total momentum after in a closed system
A positive number means right
A negative number means left
