Question

❥Anushka࿐


Q1.A train travels in a straight line at a constant speed of 60 km/h for a particular distance d and then travels another distance equal to 2d in the same direction at a constant speed of 80 km/hr in the same direction as it was in the it was previously going a) What is the average speed of the train during the whole journey.​​

Answer 1

Answer:

70 kmh-¹

Step-by-step explanation:

Average speed= total distance travelled/total time taken.

=60+80/1+1

=140/2

=70km/h

Answer 2

Step-by-step explanation:

Given :

Train travels Distance = d with speed (v1) = 60m/h

Another distance Travelled by train = 2d with speed (v2) = 80m/h

To Find :

Average speed

Formula Used :

\bullet\underline{\boxed{\sf Average \: Speed =\dfrac{Total \: Distance}{Total \: Time}}}∙

AverageSpeed=

TotalTime

TotalDistance

Solution :

★ Total Time (T)

➞ t = \dfrac{s}{v}

v

s

➞ t1 = d/60

➞ t2 = 2d/80

➞ t2 = d/40

➞ T = t1 + t2

➞ T = d/60 + d/40

➞ T = \rm{\dfrac{40d+60d}{60 \times 40}}

60×40

40d+60d

➞ T = \rm{\dfrac{d}{24}}

24

d

Average Speed = \rm{\dfrac{Total \: Distance}{Total \; Time}}

TotalTime

TotalDistance

\implies{\rm \dfrac{d+2d}{\dfrac{d}{24}} }⟹

24

d

d+2d

\implies{\rm 3d \times \dfrac{24}{d}}⟹3d×

d

24

\implies{\bf v_{av}=72 \: m/h }⟹v

av

=72m/h

Answer :

Average speed of train is 72 m/h