Question

A train Moves the speed of 40 km per hour for 3 hr next 30 kilometre per hour for 24 hour and last with 60 km per hour for 3 hour calculate the average speed

Answer 1

Answer:

Given:

Train moves with 40 km/hr for 3 hours , next 30 km/hr for 24 hours and 60 km/hr for 3 hour.

To find:

Average speed of the train

Concept:

Average speed is always defined as the ratio of total distant travelled to the total time taken to travel that distance.

Since it involves distance , average speed will always be positive and never be negative or zero.

Calculation:

$avg. \: v = \dfrac{total\: distance}{time}$

$avg. \: v = \dfrac{(40 \times 3) + (30 \times 24) + (60 \times 3)}{3 + 24 + 3}$

$= > avg. \: v = \dfrac{ 1020}{30}$

$= > avg. \: v = 34 \: km {hr}^{ - 1}$

So final answer :

$\boxed{ \red{ \huge{ \bold{ avg. \: v = 34 \: km {hr}^{ - 1} }}}}$

Answer 2

SoLuTiOn :

➡ Given:

✏ A train moves the speed of 40kmph for 3 hr, next 30kmph for 24 hr, and last with 60kmph for 3 hr.

➡ To Find:

✏ Average speed of train.

➡ Concept:

✏ Average speed is defined as ratio of total distance covered by body to total time taken by body to complete the journey.

➡ Formula:

✏ A body moving with different speeds in different time intervals. Suppose a body travels with speeds v1, v2, v3 in time intervals t1, t2, t3 respectively.

$\rightarrow \: \underline{ \boxed{ \bold{ \rm{ \pink{average \: speed = \frac{total \: distance \: travelled}{total \: time \: taken}}}}}} \: \star$

➡ Calculation:

$\rightarrow \rm \: v_{av} = \frac{v_1t_1 + v_2t_2 + v_3t_3}{t_1 + t_2 + t_3} \\ \\ \rightarrow \rm \: v_{av} = \frac{(40 \times 3) + (30 \times 24) + (60 \times 3)}{3 + 24 + 3} \\ \\ \rightarrow \rm \: v_{av} = \frac{120 + 720 + 180}{30} = \frac{1020}{30} \\ \\ \rightarrow \: \underline{ \boxed{ \bold{ \rm{ \purple{v_{av} = 34 \: kmph}}}}} \: \star$

➡ Additional information:

• Average speed is scalar quantity.
• Average velocity is vector quantity.