Physics Revision Notes PDF

physics revision ( what is force and types of it ) A force is a push or a pull acting on an object due to its interaction with another object. It causes a stationary object to move and a moving object to come to a stop. ---------------------------------------- types of it & examples -----------...

physics revision ( what is force and types of it ) A force is a push or a pull acting on an object due to its interaction with another object. It causes a stationary object to move and a moving object to come to a stop. ---------------------------------------- types of it & examples ---------------------------------------- 1. Normal Force When an object lies on a surface, the surface exerts an equal and opposite force. The component of this force that is perpendicular to the surface is called the normal force. Example: The force exerted by the table on a book lying on it. 2. Applied Force The forces applied to an object in order to displace or deform it is called the applied force. Example: The force with which a person pushes a cart. 3. Tension Force The tension or tension force is a force experienced by a rope, string, or cable pulled from the opposite end. Example: The force experienced by a rope when a person pulls a bucket of water from a well. ------------------------- units of force Weight is caused by gravity & the MASS X GRAVITIATIONAL FIELD STRENGTH of earth is 9.8N/kg 40kg child on earth (g=9.8N/kg) 40 x 9.8 =392 N EQUATION : WEIGHT = MASS X GRAVITIATIONAL FIELD STRENGTH || FORCE X DISTANCE A newton meter is for spring balance and the newton is used for weight ------------------------- resultant force : & reaction force REACTION FORCE: for every action force there is an equal and opposite reaction force. example : skating and throwing the ball too your right will have the same newtons too your left, the only difference is the direction therefore the newton force stays the same. RESULTANT FORCE: finding the resultant force means finding the overall difference if I had 2 two 30N going opposite directions the resultant would be 0 as they are balanced, if one was 5N and the other direction was 3N the resultant force would be 2. ------------------------ Speed (definition, units and calculating speed). ----------------------------------------------------------------------------------------- working it out : To work out speed, cover the S. To work out distance, cover the D. To work out time, cover the T. (practice test online) ---------------------------------------------------------------- Earthquake Waves -------------------------------------- Longitudinal waves: Movement of particles is parallel to the motion of energy (e.g., sound waves). Transverse waves: Movement of particles is at right angles (perpendicular) to the motion of energy. Surface waves: Particles travel in a circular motion. ---------------------------------------------------------------------------------------------- Ultra sound & X-rays -------------------------------------- Ultrasound allows doctors to see organs, tissues, and other structures inside the body. shows structures inside the body using high-intensity sound waves. USED IF : Diagnosis: It helps diagnose various conditions by visualizing internal structure An external ultrasound scan is most often used to examine the heart or an unborn baby in the womb. It can also be used to examine the liver, kidneys and other organs in the tummy and pelvis, as well as other organs or tissues that can be assessed through the skin. USED IN MEDICINE: -------------------------------------- X-rays are a type of radiation that can pass through your body, not seen by the naked eye and you cant feel them. They are absorbed at different rates by different parts of your body a detector on the other side of the body picks up the X-rays after they've passed through and turns them into an image. USED IF : bone fractures and breaks scoliosis (abnormal curvature of the spine) lung problems, such as pneumonia and lung cancer USED IN MEDICINE: --------------------------------------- Big Bang theory (description of the theory and the evidence we have for it) In the beginning of our Universe an explosion began, it expanded our universe outwards faster than the speed of light When cosmic inflation came to a sudden and still mysterious end, the more classic descriptions of the Big Bang took hold. A flood of matter and radiation, known as "reheating," began populating our universe with the stuff we know today: particles, atoms, the stuff that would become stars and galaxies.This all happened within just the first second after the universe began, when the temperature of everything was still insanely hot --------------------------------------------------------------------------------------- Evidence : Cosmic Microwave Background Radiation (CMB): The discovery of CMB provides strong evidence for the Big Bang. (predicted) Redshift of Distant Galaxies: Observations of the redshift of distant galaxies support the theory. Abundance of Light Elements: The chemical composition of old galaxies and stars agrees with predictions from the Big Bang.