Answer

Verified

480.9k+ views

Hint: The proper approach of the solution is first finding the distance travelled by the car.

Then we can use the formula i.e. distance= speed * time

Complete step-by-step answer:

We first need to find the distance travelled by the car in 2 hours with speed 60 km/h.

Distance= Speed X Time …(i)

Where, speed is equal to the speed maintained by the car throughout the journey and time is equal to the time taken by the car to complete the journey.

Therefore, distance= $60km/h\times 2h=120km$

Now we need to calculate the time with which the calculated distance will be covered with a speed of 80 km/h.

Equation (i) can also be written as $Time=\dfrac{Dis\tan ce}{Speed}$

Distance we have is 120 km and the given speed is 80 km/h.

Therefore, $Time=\dfrac{120km}{80km/h}$

On simplifying we have,

$Time=\dfrac{3}{2}h=1.5h$

Hence, the answer is 1.5 hours.

Note: We must remember that the speed must be the same throughout the distance travelled. Hence, the speed must be uniform and if not the formula distance=speed x time cannot be used.

In the question it is not exactly mentioned that the speed is uniform throughout the journey and the distance travelled at first must be used to calculate the time when speed increases to 80 km/h. We must be intuitive and understand these things.

Then we can use the formula i.e. distance= speed * time

Complete step-by-step answer:

We first need to find the distance travelled by the car in 2 hours with speed 60 km/h.

Distance= Speed X Time …(i)

Where, speed is equal to the speed maintained by the car throughout the journey and time is equal to the time taken by the car to complete the journey.

Therefore, distance= $60km/h\times 2h=120km$

Now we need to calculate the time with which the calculated distance will be covered with a speed of 80 km/h.

Equation (i) can also be written as $Time=\dfrac{Dis\tan ce}{Speed}$

Distance we have is 120 km and the given speed is 80 km/h.

Therefore, $Time=\dfrac{120km}{80km/h}$

On simplifying we have,

$Time=\dfrac{3}{2}h=1.5h$

Hence, the answer is 1.5 hours.

Note: We must remember that the speed must be the same throughout the distance travelled. Hence, the speed must be uniform and if not the formula distance=speed x time cannot be used.

In the question it is not exactly mentioned that the speed is uniform throughout the journey and the distance travelled at first must be used to calculate the time when speed increases to 80 km/h. We must be intuitive and understand these things.

Recently Updated Pages

what is the correct chronological order of the following class 10 social science CBSE

Which of the following was not the actual cause for class 10 social science CBSE

Which of the following statements is not correct A class 10 social science CBSE

Which of the following leaders was not present in the class 10 social science CBSE

Garampani Sanctuary is located at A Diphu Assam B Gangtok class 10 social science CBSE

Which one of the following places is not covered by class 10 social science CBSE

Trending doubts

Harsha Charita was written by A Kalidasa B Vishakhadatta class 7 social science CBSE

Which are the Top 10 Largest Countries of the World?

Banabhatta wrote Harshavardhanas biography What is class 6 social science CBSE

Difference Between Plant Cell and Animal Cell

Fill the blanks with the suitable prepositions 1 The class 9 english CBSE

How do you graph the function fx 4x class 9 maths CBSE

The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths

One Metric ton is equal to kg A 10000 B 1000 C 100 class 11 physics CBSE

Why is there a time difference of about 5 hours between class 10 social science CBSE