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www.GOALias.blogspot.com5 minutes would be much smaller thanthat covered by the bus. Would you saythat the bus is moving faster than thebicycle?We often say that the faster vehiclehas a higher speed. In a 100-metre race144Fig. 13.1 Vehicles moving in the samedirection on a roadFig. 13.2 Position of vehicles shown inFig. 13.1 after some timeit is easy to decide whose speedis the highest. One who takesshortest time to cover thedistance of 100 metres has thehighest speed.13.2 SPEEDYou are probably familiar withthe word speed. In theexamples given above, a higherspeed seems to indicate that agiven distance has beencovered in a shorter time, or alarger distance covered in agiven time.The most convenient way tofind out which of the two ormore objects is moving fasteris to compare the distancesmoved by them in a unit time.Thus, if we know the distancecovered by two buses in onehour, we can tell which one isslower. We call the distancecovered by an object in a unittime as the speed of the object.When we say that a car ismoving with a speed of 50kilometres per hour, it impliesthat it will cover a distance of50 kilometres in one hour. However, acar seldom moves with a constant speedfor one hour. In fact, it starts movingslowly and then picks up speed. So,when we say that the car has a speed of50 kilometres per hour, we usuallyconsider only the total distance coveredby it in one hour. We do not botherwhether the car has been moving withSCIENCE