Question

it a car covers half of its joureny with 72km/hr & remaining half with 15m/s. find the avg speed of car​

Answer 1

Answer:

48kmh -¹

Explanation:

Average speed is V=

time

distance

if a car travels first half with V

1

and second half of distance with V

2

then formula of average velocity is given by

V=

V

1

+V

2

2V

2

V

1

=

60+40

2∗60∗40

=48km/h

hope it's helpful to you!

Answer 2

Answer:

17.142 m/s

Explanation:

As per the provided information in the given question, we have :

• A car covers half of its journey with 72km/hr.
• It covers remaining half with 15 m/s.

We are asked to calculate the average speed of the car.

In order to calculate the average speed of the car, we'll be using the formula of average speed.

$\\ \twoheadrightarrow \quad \sf {Speed_{(avg)} = \dfrac{Total \; distance}{Total \; time} }$

★ Finding total distance :

Let us say distance covered in first half be d metre and in another half be d km. Therefore,

$\\ \twoheadrightarrow \quad \sf {Total \; distance = (d +d) \; m }$

$\\ \twoheadrightarrow \quad \bf \underline {Total \; distance = 2d \; m }$

★ Finding total time :

Total time will be equivalent to the time taken to cover the distance in first half with the speed of 72 km/h and the time taken to cover the distance in second half with the speed of 15 m/s.

Time taken in the first half :

• Speed = 72 km/h = 20 m/s
• Distance = d metre

$\\ \twoheadrightarrow \quad \sf { Time = \dfrac{Distance}{Speed} }$

$\\ \twoheadrightarrow \quad \sf { t_1 = \dfrac{d}{20} \; s }$

Time taken in second half :

• Speed = 15 m/s
• Distance = d metre

$\\ \twoheadrightarrow \quad \sf { Time = \dfrac{Distance}{Speed} }$

$\\ \twoheadrightarrow \quad \sf { t_2 = \dfrac{d}{15} \; s}$

Finding total time taken :

$\\ \twoheadrightarrow \quad \sf { Total \; time = t_{1} + t_{2} }$

$\\ \twoheadrightarrow \quad \sf { Total \; time = \Bigg \{ \dfrac{d}{20} + \dfrac{d}{15} \Bigg \}\; s }$

$\\ \twoheadrightarrow \quad \sf { Total \; time = \Bigg \{ \dfrac{3d + 4d}{60} \Bigg \}\; s }$

$\\ \twoheadrightarrow \quad \sf { Total \; time = \dfrac{7d}{60} \; s }$

Now, substituting the values in the formula of average speed.

$\\ \twoheadrightarrow \quad \sf {Speed_{(avg)} = \dfrac{Total \; distance}{Total \; time} }$

$\\ \twoheadrightarrow \quad \sf {Speed_{(avg)} = \Bigg \{ 2d \div \dfrac{7d}{60} \Bigg \} \; m/s }$

$\\ \twoheadrightarrow \quad \sf {Speed_{(avg)} = \Bigg \{ 2d \times \dfrac{60}{7d} \Bigg \} \; m/s }$

$\\ \twoheadrightarrow \quad \sf {Speed_{(avg)} = \Bigg \{ 2 \times \dfrac{60}{7} \Bigg \} \; m/s }$

$\\ \twoheadrightarrow \quad \sf {Speed_{(avg)} = \Bigg \{ \dfrac{120}{7} \Bigg \} \; m/s }$

$\\ \twoheadrightarrow \quad \sf {Speed_{(avg)} = 17.142 \; m/s }$

Therefore, average speed of the car is 17.142 m/s.