‘Time Speed Distance Work’ is an important topic for RRB exams. The concept of this topic is applied in our day to day life. Speed, Distance and Time are related to each other which can be explained with the help of the formula which is given below.
Speed = $$\frac{Distance}{Time}$$
Here from any two things, we can determine the third thing.
In case of boat and stream, relative speed concept is used where boat is going with the stream and opposite to stream called downstream and upstream respectively.
Let’s assume the speed of boat in still water is B and the speed of stream is C
Downstream speed = (B+C)
Upstream speed = (B-C)
Speed of boat in Downstream = (B+C) = $$\frac{Distance}{Time}$$
Speed of boat in Upstream = (B-C) = $$\frac{Distance}{Time}$$
In case of trains, if two trains are running in the same direction, then the relative speed will be the difference of the speed of both trains.
In case of trains, if two trains are running in the opposite direction, then the relative speed will be the addition of the speed of both trains.
Relative Speed = $$\frac{Distance}{Time}$$
Total work = Number of days $$\times$$ Number of workers
$$\frac{M{_1}\times D{_1}}{W{_1}} = \frac{M{_2}\times D{_2}}{W{_2}}$$
$$M{_1}$$ = Number of men required for one work.
$$D{_1}$$ = Number of days required for one work.
$$W{_1}$$ = Total one work
$$M{_2}$$ = Number of men required for another work.
$$D{_2}$$ = Number of days required for another work.
$$W{_2}$$ = Total another work
Total capacity of tank = Efficiency of pipe $$\times$$ Time required to fill
Q) Find out the time taken by a car to cover 910 km distance at the speed of 26 km/h.
Sol. Time = $$\frac{910}{26}$$
= 35 hours
Q) Pipe A alone can fill the tank completely in 21 hours. Pipe B alone can fill the tank completely in 14 hours. Find out the time taken by both the pipes together to fill the complete tank.
Sol. Let’s assume the total capacity of the tank is 42 units.
Pipe A alone can fill the tank completely in 21 hours.
Efficiency of pipe A = 42/21 = 2 units/hour
Pipe B alone can fill the tank completely in 14 hours.
Efficiency of pipe B = 42/14 = 3 units/hour
Time taken by both the pipes together to fill the complete tank = 42/5
= 8.4 hours
