Study Science

Speed

How to Calculate SpeedSpeed can be calculated using following formula:Speed = distance covered / time taken to cover the distance. 


Looking out for more help on Formula for Average Speed in motion by visiting listed websites.


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. 


My forthcoming post is on Formula for Wave Speed  and Formula for Wavelength  will give you more understanding about Physics.


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