How to Calculate SpeedSpeed can be calculated using following formula:Speed = distance covered / time taken to cover the distance.
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To calculate average speed:Avg. speed = (total distance) / (total time)Alternate way to calculate avg. speed is:Avg. speed = (2 speed1 * speed2) / (speed1 + speed2) ------------ (if speed is given)Note that avg. speed (sum of speeds)/(number of given speeds)Speed Word ProblemsQues.1) an object covers one round of a circular track of diameter 7/22 km in 60 seconds. Calculate speed of the object?Sol.) distance covered by the object in one round = 2 π r = 2 π (d/2) = π dAlso 1km = 1000 m and π = 22/7 Therefore distance = (22 / 7) (7000/22)Distance = 1000 mAlso speed = distance / time= 1000 / 60= 100/6 = 16.66 m/sQues.2) a man travels certain distance with a speed of 60 km/h and returns with a speed of 30 km/h. calculate the average speed of that man.Sol.)
let the distance for his destination be d km and then the total distance covered by man is 2d km.Time taken for first journey = distance/ speed = (d / 60) hrTime taken for second = (d/120) hr.Avg. speed = (total distance covered)/(total time)= = = = 240/3 = 80Therefore his average speed is 80km/hQues.3) the speed of a boat in still water is 10kmph.
It travels 24 km upstream and 24 km downstream in 5 hrs. Calculate the speed of the current?Sol.) let speed of the current be c kmph.For upstream:Distance d = 24 kmTime required for upstream journey = t1 hr.Speed of boat = (10 – c) kmph since boat is moving against the current so speed of current will be subtracted from that of boat.For downstream:Distance d = 24 kmTime required to move in downstream be t2 hr.Speed of boat = (10 + c) kmph since boat is moving with the current so its speed will be added with that of boat.Total time = t1+t2 = 5 hrsAlso time = distance/speed= 5= 5Solving, we get c2="4" c="2"Therefore speed of current is 2 kmph.Speed ExamplesSpeed of light = 299,792,458 m/sSpeed of snail = 0.001 m/sWalking speed = 1.7 m/s (varies from person to person)Orbital earth speed = 3 * 104 m/s