Question

a car travels by a uniform speed of 30 km per hour for 30 minutes and then a uniform speed of 60 km per hour for 30 minutes calculate average speed of the car​

Answer 1

Answer:

45 km/h

Explanation:

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

• A car travels by a uniform speed of 30 km/h for 30 minutes.
• Then a uniform speed of 60 km/h for 30 minutes.

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

In order to calculate the average speed of the care, firstly we need to find the total distance covered and total time taken.

Calculating total distance :

In first case :

• Speed = 30 km/h
• Time = 30 minutes or 30/60 hr

$\longmapsto\rm {Distance = Speed \times Time }$

$\longmapsto\rm {d_1 = \Bigg ( 30 \times \dfrac{30}{60} \Bigg ) \; km }$

$\longmapsto\rm {d_1 = \Bigg (\dfrac{30}{2} \Bigg ) \; km }$

$\longmapsto\rm {d_1 = 15 \; km }$

In second case :

• Speed = 60 km/h
• Time = 30 minutes or 30/60 hr

$\longmapsto\rm {Distance = Speed \times Time }$

$\longmapsto\rm {d_1 = \Bigg ( 60 \times \dfrac{30}{60} \Bigg ) \; km }$

$\longmapsto\rm {d_1 = \Bigg (\dfrac{30}{1} \Bigg ) \; km }$

$\longmapsto\rm {d_1 = 30 \; km }$

Therefore,

$\longmapsto\rm {Distance_{(Total)} = d_1 + d_2 }$

$\longmapsto\rm {Distance_{(Total)} = (15 +30) \; km }$

$\longmapsto\bf {Distance_{(Total)} = 45 \; km }$

∴ Total distance covered is 45 km.

Now, finding total time :

$\longmapsto\rm {Time_{(Total)} = t_1 + t_2 }$

$\longmapsto\rm {Time_{(Total)} = (30+30) \; minutes }$

$\longmapsto\rm {Time_{(Total)} = 60 \; minutes }$

$\longmapsto\rm {Time_{(Total)} = 1\; h }$

∴ Total time taken is 1 hour.

As we know that,

⇒ Average speed = Total distance ÷ Total time

⇒ Average speed = 45 km ÷ 1 h

⇒ Average speed = 45 km/h

∴ Average speed of the car is 45 km/h.

Answer 2

Answer:

45 kmph

Explanation:

v1=30kmph

v2=60kmph

formmula when time is divided in 2 equal parts=v1+v2/2

=30+60/2

=45kmph