Wednesday, August 31, 2011
The important formulas and values that you must know for exams and to solve problems:
Please take note of the following because they will be useful in your exams:
Click on the images to see them clearly!
Problem on circular motion - solved
the question:
An object of mass 4 kg moves round a circle of radius 6 m with a constant speed of 12 m/s.
Read the question first :
Calculate
1.the angular velocity
Answer: angular velocity= speed/readius
= 12/6
= 2 rad/s
ok this is done with the formula : angular velocity= speed/readius
the next question is
2.the force towards the center (using a=v2/r)
Answer: force = m a
= mx v2/r ok
= 4x 122/6
=96N
Rotational motion Physics A Level
Todays topic is rotational motion .
Many students take this chapter to be a difficult one, but in fact it is a very easy one :the only thing we will have to do is to compare rotational motion with linear motion and then do the questions based on the formulas we are going to derive:
Torque is considered as the force here and alpha that is angular acceleation is considered to be acceleration.
Torque is considered as the force here and alpha that is angular acceleation is considered to be acceleration
Torque= force x radius of circle
Rotational motion Physics A Level
Todays topic is rotational motion .
Many students take this chapter to be a difficult one, but in fact it is a very easy one :the only thing we will have to do is to compare rotational motion with linear motion and then do the questions based on the formulas we are going to derive:
Torque is considered as the force here and alpha that is angular acceleation is considered to be acceleration.
Torque is considered as the force here and alpha that is angular acceleation is considered to be acceleration
Torque= force x radius of circle
Many students take this chapter to be a difficult one, but in fact it is a very easy one :the only thing we will have to do is to compare rotational motion with linear motion and then do the questions based on the formulas we are going to derive:
Torque is considered as the force here and alpha that is angular acceleation is considered to be acceleration.
Torque is considered as the force here and alpha that is angular acceleation is considered to be acceleration
Torque= force x radius of circle
Tuesday, August 30, 2011
Free Fall
Free Fall
A body moving freely under gravity has a constant acceleration of 9.8 m/s2 downwards towards the centre of the earth. This can be proved by the following:
mg=ma (during free fall)
Here m gets cancelled out,
g=a
As we already know that the force gravity on 1 kg mass is 9.8 N ,therefore the acceleration of free fall is also 9.8 m/s2 .
It is evident from the following that a body moving freey under gravity , increases its speed by 9.8m/s every second.
A body moving freely under gravity has a constant acceleration of 9.8 m/s2 downwards towards the centre of the earth. This can be proved by the following:
mg=ma (during free fall)
Here m gets cancelled out,
g=a
As we already know that the force gravity on 1 kg mass is 9.8 N ,therefore the acceleration of free fall is also 9.8 m/s2 .
It is evident from the following that a body moving freey under gravity , increases its speed by 9.8m/s every second.
Free Fall
Free Fall
A body moving freely under gravity has a constant acceleration of 9.8 m/s2 downwards towards the centre of the earth. This can be proved by the following:
mg=ma (during free fall)
Here m gets cancelled out,
g=a
As we already know that the force gravity on 1 kg mass is 9.8 N ,therefore the acceleration of free fall is also 9.8 m/s2 .
It is evident from the following that a body moving freey under gravity , increases its speed by 9.8m/s every second.
A body moving freely under gravity has a constant acceleration of 9.8 m/s2 downwards towards the centre of the earth. This can be proved by the following:
mg=ma (during free fall)
Here m gets cancelled out,
g=a
As we already know that the force gravity on 1 kg mass is 9.8 N ,therefore the acceleration of free fall is also 9.8 m/s2 .
It is evident from the following that a body moving freey under gravity , increases its speed by 9.8m/s every second.
Monday, August 29, 2011
Physics A Level formulas for motion.
It is very advisable to study and learn the following formulas by heart:
v= s/t
a= v/t
v= s/t
a= v/t
The cambridge system of conducting a level physics exams
CIE provides a easy way to get a level physics qualification.
Either you can take the exam completely by doing 5 papers, or you can first do the AS/L which has 3 papers then do A2 in the second year which comprises of two exam papers.
Either you can take the exam completely by doing 5 papers, or you can first do the AS/L which has 3 papers then do A2 in the second year which comprises of two exam papers.
Sunday, August 28, 2011
SI units and modern physical measurements
I am resuming to add notes to this blog after quite a few days.
Todays topic: Measurement and Analysis.
I would like to begin with an introduction about phyiscs.Physics is defined as putting the theories of nature into mesurements.
The SI unit of mass is kilogram (kg):
The modern mass unit that is a kilogram is is based on the mass of a platinum block placed in the french bereau of measurement.
The SI unit of distance is the meter (m):
This modern assumption of distance is based on the distance travelled by light waves in 1/300000000 second(that is 300 million time of a second)
The SI unit of time is the second (s):
The modern value of a second is based on a specific number of oscillations pf a ceasium isotope.
The above details will not be tested in depth at exams,but it is still vital for you to remember them because they will be of great help in understanding to solve problems.
Saturday, August 20, 2011
What's the rate of change dm/dt of the mass m(t)?
Gas moves out of a pipe at a rate of v m/s which has a cross-sectional area of A .The density of the gas is p.
Our task is to prove that dm/dt=pAv
OK lets begin with enthusiasm:
p(density) =mass/volume (we learnes this equation in a lower class)
therefore mass=density x volume
ie m = pV
we already know that volume= area x height
we already know that height= velocity x time
therefore mass = density x volume
=density x area x height
=density x area x velocity x time
= p x A x v x t
Therefore dm/dt =p x A x v
THE RATE OF CHANGE IN MASS IS EQUAL TO THE DENSITY TIMES THE CROSS SECTIIONAL AREA TIMES THE VELOCITY .
Our task is to prove that dm/dt=pAv
OK lets begin with enthusiasm:
p(density) =mass/volume (we learnes this equation in a lower class)
therefore mass=density x volume
ie m = pV
we already know that volume= area x height
we already know that height= velocity x time
therefore mass = density x volume
=density x area x height
=density x area x velocity x time
= p x A x v x t
Therefore dm/dt =p x A x v
THE RATE OF CHANGE IN MASS IS EQUAL TO THE DENSITY TIMES THE CROSS SECTIIONAL AREA TIMES THE VELOCITY .
Wednesday, August 17, 2011
The law of conservation of momentum
This law states that momentum is neither created nor destroyed in a collision or whatever the case may be.
Momentum change and force.
Momentum:
Newtons first law: A body will continue in a state of rest or in uniform motion unless an external force acts on it .
So it is evident from this law that we have to appply external forces to make the body move,and also we have to provide external forces to bring a body to rest or to increase the speed of the body.
Newtons second law: The rate of change of momentum is directly proportional to the force applied.
The equation derived from this important law is : force= change in momentum
change in time
As we also know the equation for momentum which is
momentum = mass X velocity
Monday, August 15, 2011
Vectors and Scalars
Displacement and velocity are examples of vectors because they have a magntude and a direction .To make things simpler lets put this is simple terms.
The properties of vectors are:
1.they have a magnitude
2.they have a direction( only vector quantities ahve direction)
Distance and speed are examples of scalers Such quantities have only a magnitude and no direction.
Whether it is O/L or A/L You need to differenciate and identify scalers and vectors which are important parts of basic physics.
You will be tested in exams asking you to say whether a given quantity is a vector or a scaler.
If you have any further doubts about the specifications about the differenciations of speed and velocity and the problems involved in them please be kind enough either to email me at veeradinesh85@gmail.com or just leave a comment below.Any type of doubts are welcome even ifthey are not from this section.
The properties of vectors are:
1.they have a magnitude
2.they have a direction( only vector quantities ahve direction)
Distance and speed are examples of scalers Such quantities have only a magnitude and no direction.
Whether it is O/L or A/L You need to differenciate and identify scalers and vectors which are important parts of basic physics.
You will be tested in exams asking you to say whether a given quantity is a vector or a scaler.
If you have any further doubts about the specifications about the differenciations of speed and velocity and the problems involved in them please be kind enough either to email me at veeradinesh85@gmail.com or just leave a comment below.Any type of doubts are welcome even ifthey are not from this section.
Speed and velocity
Dynamics Physics a level
Motion in a srtraight line.
Speed is different from velocity .Speed is the distance moved in a unit time , while velocity is the distance moved in a unit time in a particular direction.
We can assume that a car is moving in a stright line with a velocity of 5 m/s ,than it is evident that the car travels a distance of 5m in one second without any change in direction,
The equation which is used is: velocity = distance moved /time taken (use this formula in exams and when doing problems)
Example: A motor bike travels 1000 m in 6 minutes,find the speed of the motor bike? (dear students take note of the wording please the question asks for the speed of the bike as it doesnot say that the bike travelling in a specific direction.
If you have any further doubts about the specifications about the differenciations of speed and velocity and the problems involved in them please be kind enough either to email me at veeradinesh85@gmail.com or just leave a comment below.Any type of doubts are welcome even ifthey are not from this section.
Motion in a srtraight line.
Speed is different from velocity .Speed is the distance moved in a unit time , while velocity is the distance moved in a unit time in a particular direction.
We can assume that a car is moving in a stright line with a velocity of 5 m/s ,than it is evident that the car travels a distance of 5m in one second without any change in direction,
The equation which is used is: velocity = distance moved /time taken (use this formula in exams and when doing problems)
Example: A motor bike travels 1000 m in 6 minutes,find the speed of the motor bike? (dear students take note of the wording please the question asks for the speed of the bike as it doesnot say that the bike travelling in a specific direction.
If you have any further doubts about the specifications about the differenciations of speed and velocity and the problems involved in them please be kind enough either to email me at veeradinesh85@gmail.com or just leave a comment below.Any type of doubts are welcome even ifthey are not from this section.
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