hey guys in this video I'm going to be going through all the formulas which you have to know before you go into your exams because remember that physics is largely Matt based so you are going to expect a huge number of calculations and there's no way that you could do well on these type of questions if you haven't bothered to learn all the equations so let's get started the first one we've got here is under the first chapter of motion whereby speed is the distance traveled over the time taken or in another word it's the velocity you can also write them as v = d / T remember that the distance always is in meter and time is in second so meters divided by second will give us the unit for velocity which is m/ s units are extremely important in physics and remember the SI you need for each quantity for distance is always in meter and time in seconds next acceleration is the change in velocity per unit time so to find the change of velocity we're going to take the final velocity minus the initial velocity over time acceleration means an object speed is increasing over time so the final velocity will always be higher than its initial velocity if the question gives you information such as object at rest this means that the initial velocity here would be at 0 m/s and the unit for acceleration is m/s / second giving us m/s squar sometimes you may be asked to calculate speed from a distance time graph and you can get the speed speed by taking two points of the graph and then use the formula of gradient to get the speed and if you're given a speed time graph the gradient of this graph will represent its acceleration and to get the distance traveled for the object you can find the area below the graph and if your speed time graph looks something like this then finding the gradient would be a little bit more complicated whereby you're going to draw a tangent for the time of acceleration they're looking for and then repeat the same thing get two points furthest from each other and use the formula of gradient to obtain the acceleration next under mass and weight you must know the difference of mass and weight mass is the measure of quantity of matter whereas weight is going to be the mass multiplied by its gravity so w = to M * G and the value of G if on Earth is always given which is 9.8 make sure that mass is in kilogram and the unit for weight will be in Newtons next density density is the mass per unit volume so the formula is m/ V if the mass is in kilogram and the unit is in M Cub then the unit for density would be kilog per M Cub questions regarding density are usually quite straightforward and usually these types of question are combined with chapter 2 for specific heat capacity where they will give you the volume and density and they'll ask you to find the mass to be substituted into the formula of energy so to do that mass would be density time volume next under the subtopic of forces you're going to have to learn a lot of formul one of them is based on the principle of hooks law whereby the extension of a spring is directly proportional to the force applied provided that its limit of proportionality is not exceeded make sure you know the principle of hooks law because you could be asked and this would give you two marks and the formula for this is f = to K * X the unit for force is Newton and extension of spring could be in centim or meters depending on the question so the weight applied here would be your Force make sure is in Newton if they have given you the mass in kilogram then make sure to convert it into Newton by multiplying by 9.8 and depending on how much the spring has extended that would be the value of x all right next you've got the Newton 3 laws I'll let you guys read this by yourself however from Newton's Second Law you will learn another formula which is very popular resultant Force equals to mass time acceleration F = to M A the unit of acceleration is m/s square mass is in kilogram and the force will be in Newtons moving on to calculate moment you're going to take the force times distance and the distance has to be perpendicular from the pavot point and it will help in your calculation if you understood that there is no resultant force and no resultant moment when the object is in equilibrium this means that the anticlockwise moment and the clockwise moment is equal to each other when they are in equilibrium the unit of force is in Newtons and distance is in meters so that gives us the unit for moment Newton M next up for momentum which is also a very popular type of question where momentum is the mass times velocity the mass of the object is in kilogram and velocity is met second this gives the unit for momentum kg m/s this type of question can be really tricky because momentum is a vector quantity that mean it comes with a Direction so in case you ask to find the momentum of this dummy you're just going to take the mass of this dummy and multiply it with the speed that it is moving and that's it you're going to get the answer however if you're asked to calculate the change of momentum then you're going to do the mass times its final velocity minus the mass times its initial velocity so the initial velocity is moving in this direction this will be in positive and when the ball bounces back it's going to be in the opposite direction so your final velocity will now be in a negative value always pay attention to these types of question this is going to make a huge difference to your answers so make sure you do not forget the symbols and these types of question will always continue to ask you on impulse whereby impulse is equal to the change of momentum and impulse is the force time time so Force time time could also be the change of momentum so once you have gotten your change in momentum it can be used to get the impulse and you will be able to obtain your time or Force depending on what the question needs next underwork energy and power power is known as has the work done or energy transferred per unit time so here's the formula power equals to work done over time taken work done is measured in jewels and time in second so the power will be juw per second or you can write Watts which is W if you're not given with the work done you could instead use the change of energy per unit time sometimes the question will ask you to calculate the energy so you can just rearrange it by multiplying power with time just make sure that your time is always converted into seconds and the unit for energy is in Jewels there are two types of energy that you have to pay attention to the first one is kinetic energy which is half MV s and the second one is potential energy which is mass time gravity * H so in this question if they ask you to find the H you can assume that the gpe is equal to the kinetic energy you could easily cancel out the M on both sides and then use the velocity of the waterfall let's say m/s and then the value of G is always 9.8 and you can obtain your H easily and next off you've got efficiency whereby depending on the question if they want you to find the efficiency of energy or power it's always going to be output over the input and multiply it by 100 efficiency have no unit so you're just going to leave your answer as percentage and the last topic for this chapter is to calculate pressure whereby it is force over area force is in Newton and when you're asked to calculate area make sure it is in me Square this will give the unit of pressure which is n/ m² and if the question is related to pressure in liquid then the formula would be h r g g depends on the density of liquid that is being tested in the question and then G is a fixed value of 9. H and the height here is depending on the depth of the object from the surface level so you can just put in all the values and get your answer in Newton SL M square or you can leave your answers in Pascal all right moving on to chapter 2 this chapter doesn't have much formulas or calculations involved make sure you know what is absolute zero which is the lowest temperature at 273° C you might be asked to convert Kelvin into de C and you can do this by adding 273 and according to boils law P1 V1 is equal to p2v2 for instance if you have been given pressures on before and after and if you are asked to calculate another volume then this is when you would apply boil slw given that the temperature is constant and the most popular formula or calculation related to this chapter is regarding the specific heat capacity anytime you see specific heat capacity you can immediately write down the formula of MC Theta Theta is the change of temperature C is the specific heat capacity mass is always given in kilog or gam so make sure you always convert it into kilog and the energy will be sometimes they will not give you the mass because the density and volume is provided so as mentioned previously you can use the formula of density rearrange it to get the mass for this formula and moving on to chapter three under the general properties of wave which is the number of waves passing per second which can be calculated by one over time and time here would be in seconds and the unit for frequency is in hertz h z and next if you're asked to calculate the speed of a wave you can use the frequency times Lambda Lambda here is the wavelength and wavelength will be in meters wavelength can be calculated from one p to another this distance would represent the Lambda next under the subtopic of light you can be asked to calculate the refractive index which is the speed in air over the speed in medium or sin Theta which is the angle in air over the angle in medium so this would be the incident angle and this here would be the refracted angle sometimes they might trick Q by giving you the angle over here so be sure to get the incident angle you're going to do 90 minus the angle which is given CU you always want to find the angle between the normal and the line the normal and the reflected Line This angle and another formula to find reflective index is 1 / sin c c here represents the critical angle so let's say when you're asked to calculate critical angle it would be refective index 1.5 1 / sin C to get C you're going to do shift sign 1 / 1.5 don't forget when bringing shift to the other side it's going to be C to the^ -1 next subtopic on sound you will learn about Echoes which are a reflection of sound wave the formula related to this is the same as the formula of speed which is distance travel over time taken however questions related to Echo can be a little bit tricky so let's look at an example it's mentioned here that ultrasound is used to detect the depth of the ocean so let's say this is the bottom of the ocean the ultrasound pulses are emitted from the transducer on a boat and some of the pulses are reflected by the bottom of the ocean back like this so the shortest time between the Su weights being emitted and detected this takes 0.52 seconds that means going down hitting the bottom and coming back up takes 0.52 seconds and the speed of this wave is moving at 1.5 km/s and you asked to calculate the distance so we can rearrange this to get speed time time so the speed is 1 5 and the time is 0.52 giving us 0.78 km so remember the distance travel is going down to the bottom and then coming back up so the total distance traveled is 0.78 KM but you're asked to find the distance between the boat and the ocean floor which is the height therefore you're going to take this value and divide it by 2 which is 0.36 km or 360 M just remember that when question are related to Echo you usually have to divide your distance Distance by two because the distance goes one way and come back as an echo in the opposite direction next moving on to chapter 4 chapter four is probably one of the most difficult chapter in your syllabus there are as many calculation as there are theoretical questions so if you don't understand much on the theory at least try to focus on the formulas and the calculations so you get to score a maximum mark on these types of question firstly you've got current which can be calculated by charge over time the unit for charge is Kum and the unit for time is in seconds and the symbol of current is I and the unit is a which stands for ampere next you've got electromotive Force make sure you know what is the difference between electromotive force and potential difference they are both represented by the symbol V electromotive force is the voltage across the batteries like this and for potential difference is more for the voltage across a component so EMF can be calculated by the work done over charge work done is in watts w and Q is in Kum and the unit for EMF and potential difference both are in voltage next up for resistance you should know that resistance is directly proportional to length but inversely proportional to area this means that the longer the length the higher the resistance if the length here was 5 m and this is 10 m and resistance given here is 2 ohms then automatically you should know that the resistance resistance here is 4 ohm since it is directly proportional it will increase at the similar ratio however resistance on the other hand is inversely proportional to the cross-sectional area the bigger the cross-sectional area the lower the resistance let's say this wire has a radius of 5 cm then the cross-sectional area would be 25 pi and if they mention that the resistance is 2 ohm let's see how it affects the resistance if the wire was double sized meaning the radius will now be 10 and the cross-sectional area becomes 100 Pi instead so this increases by four and your resistance will decrease by four so this new resistance now will decrease to be 0.5 ohms and if resistance were asked to calculate from a circuit then you should know that according to ohms law which states V = to I * R if we rearrange this we will get R is voltage over current now let's say if you're looking to find the current of this circuit you are going to need the resistance and you can calculate the resistance by adding the resistance of each component if the resistance here was 2 ohm and this was 3 ohm then the resistance of the entire circuit will now be 5 ohm and you can now find the current by using ohms law whereby current is voltage over resistance so 3 over 5 will give us the current of the circuit and when also to calculate the total resistance for a parallel circuit the formula is a little bit different you're going to take 1 / R total equal to 1 / 3 + 1 / 3 giving us 1 / R total 2 over3 but this is not our final answer you have to remember to inverse this so it's going to be 3/2 and if you are asked to calculate resistance when given a current voltage graph you can get the resistance by looking at the gradient of the graph because the gradient of the graph would be 1 over the resistance just remember that the steeper the gradient the smaller the resistance next up we've got electrical power which is the transfer of electrical energy per second so we can calculate power by multiplying current with the voltage remember sometimes the current will be given in milliamp so to convert milliamp into ampere you're going to divide it by 1,000 and next you've got the equation for energy transferred which can be calculated by I current V voltage and time and if you realize IV is also the power so energy can also be calculated by power time time and next off you've got potential dividers when two resistors are arranged like this it can be used as a potential divider this may look complicated but actually it is using the concept of ratio to split the total input voltage for the two resistors based on their resistance so this will be the voltage in and let's say this is the voltage out that we are looking for so the voltage in would be nine and the voltage out is what we're looking for if we're looking for the voltage in then we're going to put the total resistance of the whole circuit which is 3 ohms cuz we adding them up together and the we out the resistance opposite to it is one so rearranging this the we out is 3 voltage similarly if you just try to understand this according to ratio we're trying to split 9 voltage to both of this resistor in the ratio of 2 to 1 since this has a higher resistance it would get a higher voltage this has a lower resistance it would get a lower voltage so in the ratio of 2 to 1 we split this into fraction and multiply the total you would get three voltage and 6 voltage so six voltage here and three voltage here so you can look up the parti question which I have linked at the top of this video to look at an example for this type of question and last part of this chapter is electromagnetic effects make sure you know what is a simple Transformer how it works this is what it looks like when you're given with a diagram of Transformer they're either asking you to calculate the number of turns of coil the input output voltage or the current if they want you to find the number of coil then they will give you the primary and secondary voltage and if they're asking you to find the secondary voltage then they'll give you the number of turns for primary and secondary coil and this works the same if they're asking you to calculate the current in primary and secondary coil so you just have to use this formula if you're being tested on power losses in cable then there's another formula for power which which is p = to i² resistance if you don't know which formula to use in your exam questions then always list down whatever information is given in the question let's say the question gives you current and the question gives you resistance and then they want you to find power so you can see that this formula over here consists of all the quantities that is being tested in the question so this is why remembering formulas can be really helpful when you want to tackle and solve a calculation based question and next move moving on to chapter 5 chapter 5 have no formulas that you have to memorize but you will be tested on how to write nucle notation and there will be question that is related to half life which might need you to calculate but no formulas for nuclear notation let's say they mention in the question that uranium 230 and then you can get the proton number from your periodic table decays to form another element with helium so you should know that helium has the nuclear notation of 4 to2 which is similar as Alpha then to find what element is being released you're going to look at its proton number so the proton number adds up to give you 92 meaning that the proton number here is 90 and then as for the nucleon number is the same it has to add up to give you 230 so over here would be 226 and then you're going to look up your periodic table to see which element has the proton number of 90 and you're going to write your element so what you should remember is Alpha DK which has 4 and 2 nucle notation beta is 0 and -1 and Gamma has zero and then as for halflife calculation when you are given with the sample halflife or count rate per minute the first step that you should always do is remove your background radiation so let's say it's 120 count per minute and there's always 20 count per minute as your background remove this to get the counts per minute for your sample and then half life meaning that it will reduce into half let's say the half life given is 5 days this mean that 5 days represents your sample becoming half so in another 5 days your sample will become 20 counts per minute so if they want to find out how many days does it take to reach from 100 to 10 counts per minute then you can keep dividing sorry this is 25 and I'll change this to 12.5 so keep dividing until you arrive this value you've divided 1 2 and three times so it went through three half life since each half life is 5 days that means the total is 15 days to arrive from 100 to 12.5 L per minute and if you are asked to give the readings on your guer moer or on the device then you have to add back with your background radiation which is 20 counts per minute so after 15 days the reading would be 32.5 counts per minute because 12.5 is what happened after three half life always don't forget to add back your background radiation okay and and the last chapter you should know the formula for orbital speed which is 2 pi r / T the velocity here is how fast an object is orbiting another object let's say like the moon moving around the Sun and then the radius would be from the center of the Sun to the Center of the Earth in this types of question the time could be anything depending on what the unit of speed is let's say if the speed is in kilomet per hour then make sure your radius is in kilometer and your time has been converted into hours if it's given let's say in 365 days then multiply it with 24 to change it to hours and next make sure you know the value for Speed of Light which is 3 * 10 ^ of 8 m/s let's say you are given with the distance of two objects and you want to find what is the time taken for the light to reach let's say from the Sun to Earth so the speed of the light is traveling at this value and the distance is 100 km pay attention here that the speed of light is in meters so you have to convert this also into meters and that's how you're going to get your time the distance over the speed of light and for the second part of this chapter you must know that one light here is equal to 9.5 * 10 ^ of 15 M and that Hub constant can be calculated by recession velocity over distance recession velocity is how fast the Galaxy is moving away from Earth and the distance here is how far that Galaxy is away from Earth we can plot a graph for the distance versus recession velocity and the gradient of this graph is what represents the Hubble constant which is 2.2 * 10 ^ of -18 per second and if we inverse The Hub constant which is recession velocity over distance we can actually find the AG of the universe and this is the evidence that all the matter in the universe was present at a single point all right so that's all the formulas and calculation and some important things that you should remember if there are any formulas that I have missed out please share it in the comment section below and for those of you taking your exams on this upcoming Monday I wish you best of luck thank you bye-bye take care