Speed Calculation PDF

[{ri-{D If a car is running slorv, rve say that tts speed ts iou-. And it a car is running fast, then we say that ii, ,p."a is high. Thus, the speed of a body gives us an idea of how slow o, fu-ra tfruiU"ay rs moving. We can now define the speed of a moving body as follows: Speed of a body is the d;...

[{ri-{D If a car is running slorv, rve say that tts speed ts iou-. And it a car is running fast, then we say that ii, ,p."a is high. Thus, the speed of a body gives us an idea of how slow o, fu-ra tfruiU"ay rs moving. We can now define the speed of a moving body as follows: Speed of a body is the d;;;arrt trurr"rfed by it per unit time. The speed of a body.." " ;;;;.ulated by dividing the 'Distance travelled'by the"Tirn. il;; to travel this distance. So, the formula for speed can be written u* Speed = If , ;,\;.'... E-' + Distance travelled 'i., 1 :l'; Time taken a body travels a distance s in time f, then its speed z is given by: Y=- s t where, u = speed and = distance travelled f = time taken (to travel that distance) s suppose a car travels a distance of 100 kilometres in 4 hours, then the speed of this car is given by: ioo kilometres SPeed -- or Speed 4 hours 25 kilometres per hour (or 25km/h) Thus, the speed of this car will be 25 kilom etres per hour. This means that the car travels a distance of 25 kilometres every one houri The above given formula for calculating speed has three quanti ties in it: Speed, Distance travelled and Time taken. If we are given the values of any two quantitie s, then th e value of third quantit,v can be calculated by using this formula. The SI unit of distance is metre (m) and that of time is second (s), therefore, the SI unit of speed is metres per second which is written as m/s or ms-l. The small values of speed are expressed Figure t l Speedometer and in the units of centimetres odometer of a car This speed ometer shows per second rvhich is written a peed of 85 km/h s as crn/s or cm s-i. To express and odometer shows a reading high speed values, we use the unit of kilometres per distance travelled by the car of 2.0 km for the so far. The distance hour, written as km.p.h. or km/h or km h- 1. Please travelled suggests tha t it is a brand new car. note that if we have to co mpare the speeds of a number of bodies, then we must express of them in the sam,. units. the speeds Speed has magnitude only, it has no specified direction, therefore, of all is a scalar quantity. speed The speed of a running car at any instant of time is shown by an instrument which is fixed in the carled.speedometer, The gives the rpe.d rn kilometres p., ;a1 r,ou.. The distance travened il*ll;: l4 'p"tao*ir f;:ffi:: ,"1;T#'i',*.,, cailed'odometer' which i" ur,o^i,,,,arred in rhe car. rt Motion