General Physics 1 PDF

Lesson I: Units and Measurement GENERAL PHYSICS 1 WORK, POWER AND ENERGY WORK is the product of force and displacement resulting from the application of force. The unit of Work is Joule ( 𝑱 ). 𝑾𝒌 = 𝑭 𝒙 𝒅 𝑾𝒌 = 𝑭𝒅𝒄𝒐𝒔𝜽 𝑭 = Force applied (in Newtons) 𝒅 = D...

Lesson I: Units and Measurement GENERAL PHYSICS 1 WORK, POWER AND ENERGY WORK is the product of force and displacement resulting from the application of force. The unit of Work is Joule ( 𝑱 ). 𝑾𝒌 = 𝑭 𝒙 𝒅 𝑾𝒌 = 𝑭𝒅𝒄𝒐𝒔𝜽 𝑭 = Force applied (in Newtons) 𝒅 = Displacement (in meters) θ = Angle between force and displacement Example: 1 A crate is moved 2m along a horizontal floor at a constant speed by a force of 50N. How much work is done on the crate by the force. Given: 𝐹 = 50 𝑁 𝑑 =2𝑚 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑡𝑜 𝑓𝑖𝑛𝑑: 𝑊𝑘 𝑊𝑘 = 𝐹 𝑥 𝑑 = 50 2 = 100𝐽 Example: 2 A crate is moved 2m along a horizontal floor at a constant speed by a force of 50N which makes an angle of 30 degree above the horizontal. How much work is done on the crate by the force. Given: 𝐹 = 50 𝑁 𝑑 =2𝑚 𝜃 = 30 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑡𝑜 𝑓𝑖𝑛𝑑: 𝑊𝑘 𝑊𝑘 = 𝐹𝑐𝑜𝑠𝜃𝑑 = 50(2) cos 30 = 86.6𝐽 Example: 3 A mechanic pushes a 1000 kg car along a flat road over the distance of 20 meters. How much work does the mechanic do on the car? Given: 𝑚 = 1000𝑘𝑔 𝑑 = 20 𝑚 𝑁𝑜𝑡𝑒: 𝐹 = 𝑚𝑔 POWER is the speed or rate of work. The unit of Power is watts ( 𝑾 ). 𝑾𝒌 𝑷= 𝒕 𝑾𝒌 = Work (in joule) t = Time (in second) Example: How long will it take a 25000W motor to lift 90kg block 35m high Given: 𝑃 = 25000𝑊 𝑚 = 90 𝑘𝑔 𝑑 = 35 𝑚 𝑡 =? ENERGY ability to a work. Types of Energy Kinetic Energy - Energy of an object due to its motion. Potential Energy - Energy stored due to an object’s position or state. Kinetic Energy - Energy of an object due to its motion. 𝟏 𝑲𝑬 = 𝒎𝒗𝟐 𝟐 𝒎 = Mass (in kilograms) 𝒗 = Velocity (in meters per second) Example: A 3kg block slides on a frictionless surface at 20m/s. How much kinetic energy does it have? Given: 𝑚 = 3𝑘𝑔 𝑣 = 20 𝑚/𝑠 𝟏 𝑲𝑬 = 𝟑(𝟐𝟎)𝟐 = 𝟔𝟎𝟎𝑱 𝟐 Potential Energy - Energy stored due to an object’s position or state. Gravitational Potential Energy: where: 𝑷𝑬 = 𝒎𝒈𝒉 𝒎 = Mass (in kilograms) 𝒈= Acceleration due to gravity (9.8 m/s²) 𝒉= Height (in meters) Example: Find the potential energy of a 57kg student that goes up on the stairway with height of 7.98 meters? Given: 𝑚 = 57𝑘𝑔 𝑣 = 7.98𝑚 𝑷𝑬 = 𝒎𝒈𝒉 = 𝟓𝟕 𝟗. 𝟖𝟏 𝟕. 𝟗𝟖 = 𝟒𝟒𝟔𝟐. 𝟏𝟖 𝑱  Activity 2 1. A 25kg crate is lifted from 230m above the ground in 350 seconds. a. How much work is required to lift it into the air b. What is the average power exerted on the crate. 2. A 7.5kg rock moving in space has 438J of kinetic Energy. How fast is it moving? 3. Using a rope, a fireman climb the building vertically up to a distance of 9 meters. If his potential energy is at that point is 3950 joules, what is the weight of the fireman? MCSI-SHS Thank You ! Enjoy the rest of the day! - Sir Allen