Physics P8 9 And 10 Flashcards
What is a vector ?
A vector is a quantity that has size and direction .
What is a scalar quantity ?
A scalar quantity has size but no direction
What are 5 examples of scalar quantities ?
Mass , power , energy , time and speed .
What are 5 examples of vector quantities ?
Displacement , velocity , force , weight and acceleration .
What does displacement mean ?
A measure of how far an object moves in a given direction .
What is acceleration ?
The rate of change in velocity
What is speed ?
The measurement in the increase of distance .
What is velocity ?
It is the speed of a given direction
What is mass ?
The amount of an object that is present .
What is weight ?
The force acting on an object due to gravity
What is a force ?
A force is a push or pull on an object with direction .
What is energy ?
Energy is the amount of work done without a direction .
What is power ?
The ability to do work with speed .
How can a vector be shown on paper ?
An arrow showing the direction the vector is going towards in . The size of the vector can also be shown by the size of the arrow .
What are 4 examples of a contact force ?
Air resistance
Friction
Stretching
Tension
What is the difference between a contact force and a non contact force ?
A contact force is physically touching an object to make it move . Whereas non contact forces do not require the objects to be toucning .
What is newtons third law of motion ?
When two objects interact with one another , they both exert equal and opposite force on each other.
What is friction ?
Friction is the force exerted by a surface against an object when it moves across it .
What is a resultant force ?
A resultant force is the the combined effect of multiple forces acting on a single object .
What happens when a resultant force is zero ?
The forces acting on the object are balanced
How can resultant forces be shown ?
In a free body diagram
What is the centre of mass of an object ?
The centre of mass of an object can be thought of as the point at which its mass can be thought of as being concentrated .
How can the centre of mass of a regular object be found ?
By drawing lines and where they meet is the centre of mass
What are the four steps in finding the centre of mass in an irregular object ?
- Make sure you have a retort stand , a cork pin and a plumb line .
- Then you find two points of an object or shape , then let the plumb line hang from one point and draw a line along it .
- Next hang the plumb line at the second point and draw a second line along it .
- The centre of mass will be the point at which those two lines cross .
How do you calculate speed ?
Distance divided by time
What happens when you start increasing or decreasing velocity ?
Your accelerating or decelerating
What is the formula for acceleration ?
Final velocity - initial velocity divided by 2 x time
What is the formula for velocity ?
Change in velocity divided by change in time .
What is the formula for force ?
Force = mass x acceleration
What is newtons second law ?
When you increase the force on an object you will increase the acceleration applied on to it .
What does newtons third law depend on ?
The mass of the object
What is the units for mass ?
Kg
What is the unit for weight ?
Newtons
What is the formula for weight ?
Weight = mass x gravitational field strength
What is terminal velocity ?
Constant velocity
What is the equation for total stopping distance ?
Total stopping distance = Thinking distance + braking distance
What is the stopping distance ?
The distance it takes for the vehicle to stop
What is the thinking distance ?
The thinking distance is the distance travelled between the driver realising he needs to brake and actually braking.
What are three examples of what could effect the braking distance of a vehicle ?
The conditions of the road , the brakes and the tires
What is the equation for deceleration ?
Final velocity squared - initial velocity squared divided by 2 x distance
What is the equation for braking force ?
Mass x acceleration
A car of mass 1000kg moving at 25 m/s in a distance of 75 metres . Calculate the deceleration of the car and the braking force .
0 squared - 25 squared divided by 2 x 75 = - 4.16 m/s squared = deceleration
1000kg x -4.16 m/s squared = -4.166N
What is the equation for momentum ?
Velocity x mass
What is momentum ?
Momentum is the measure of how much motion an object has .
What is an elastic object ?
An elastic object is one which regains its shape when a force deforms it.
Where does the energy that causes an elastic object to deform go ?
It is stored as elastic potential energy
What is tension ?
This when a force pulls on the object .
What does it mean if something is proportional ?
The same size and amount to something else for example as one variable increases another , another variable will increase at the same rate .
What is hookes law ?
The extension of a spring is directly proportional to the force applied .
What is the equation for the force applied on an object ?
Springs constant x extension
