P4 Flashcards
What is a force?
It is a push or pull on an object that is caused by it interacting with another object
What are contact forces?
- This is when objects are touching when the forces is acting
- For example-Friction is a contact force between two objects that slide past each other which prevents motion
What are non-contact forces?
Forces between objects that are not touching each other
What is newtons third law?
- When two objects interact, the foces they exert on each other are equal and opposite
What is mass?
The amount of matter in an object-Kg
What is gravity?
The force of attraction between masses
What is weight?
- A downward force
- weight(N)= Mass(Kg) x gravitational field strength(N/Kg)
What are scalars?
- Numbers that tell you the size of something youre measuring
- for example mass
What are vectors?
- tells you the size of something and the direction of it
- for example force-as it has a size and can be applied in a specific direction
How is the motion of an object described?
By its:
* speed
* direction of travel
* whether its speed is changing
How do you calculate speed?
Average speed(m/s) = distance(m) / time(s)
What is acceleration?
- The change in velocity of an object over a certain amount of time
- Speeding up-acceleration
- slowing down-deceleration
What is the equation for acceleration and constant acceleration?
- Acceleration(m/s(power of 2))=Change in speed(m/s)/Time taken(s)
- Final speed(power of 2)-initialspeed(PO2) = 2xAcceleration(m/s(PO2))xDistance(m)
What do distance time graphs tell you?
- Different parts describe motion of the object
- Gradient-average speed
- Steeper means faster
- Flat section means stopped
- straigh uphill means steady speed
- Curves represent acceleration
- steepening means speeding up
- leveling off means slowing down
use the gradient exaquation to work out average speed= change in y /// change in x
What do velecoity time graphs tell you?
- Used to tell you average accelration
- Flat- steady velocity
- steeper the graph means the more the avareage acceleration or deceleration
- /-acceleration
- -deceleration
- straight line-constant acceleration
- Area under any section of graph is equal to the distance travelled in that time interval
use the gradient exaquation to work out average acceleration= change in y /// change in x
What is a resultant force?
- It is the overall force on a point or object
- found by adding forces on the same direction then taking it away from the forces on the other direction
What is newtons first law?
- If the resultant force on a moving object is zero, it will continue to move at a constant speed in a straight line
- If the resultant force on a stationary object is zero, the object will remain stationary
What is momentum?
- The greater the mass of an onbject the greater its velocity, the more momentum it has
- momentum(kg m/s)=mass(Kg) x velocity(m/s)
What is newtons second law?
- The change of momentum is proprtional to the size of the resultant force ans the time over which the force acts on the object
- Change momentum(kg m/s)=resultant force(N)xTime for which it acts(s)
- Force(N) = mass(kg) x acceleration(m/s(Power of 2))
What is the law of conservation of momentum?
In a collision when no other external forces act, momentum is conserved-i.e. the total momentum after a collision is the same as it was before
What is inertia?
The tendency for an objects movement to remain unchanged- i.e. stationary objects tend to remain stationary and moving objects tend to keep moving
What is a moment?
- The rotational effect of a force
- Moment of a force(Nm) = force(N) x distance(m)
What are levers?
- Transfers the rotational effect of a force
- increases the distance from the pivot that the force is applied-increasing the size of the moment created
- useful for lifting things and moving things easier
What are gears?
- Circular disks with teeth around them
- The teeth of the gears interlock and cause other gears to move
- Due to this linkage, when one gear is spinning clockwise it will cause the next one to spin clockwise this alternates when you go from gear to gear
- force does not change within gears
- smaller gears turn quicker than larger gears
What is stopping distance equation?
stopping distance= reaction distance + braking distance
What is work done?
- It is when a force makes an object move and energe is transferred
- work done(Nm or J) = force(N) x distance(m)
What is the equation for gpe and kinetic energy?
gpe(J) = mass x g field strength(N/kg) x height(m)
kinetic energy= 0.5 x mass(kg) x speed(m/s)(power of 2)
What is power?
- The rate at which energy is transferred(or work is done) in a system
- power(W) = energy transferred (J) / time (s)
What is inertial mass?
- A measure of how difficult it is to change the velocity of an object
- Force(N) = mass x (acceleration(m/s2)
What is friction?
A force between two objects in contact trying to slide past one another.
Opposes the direction of motionn
What is kinetic energy?
Energy an object possesses due to motion
