A car travels from A to B at a speed of 20 km h_1and returns at a speed of 30 km h_1. The average speed of the car for the whole journey isa)5 km h_1b)24 km h_1c)25 km h_1d)50 km h_1Correct answer is option 'B'. Can you explain this answer?

Question

Answer

Let distance from A to B be x

Time for travel from A to B= x/20

Time for travel from B to A= x/30

Hence,speed for total distance 2x is:

Answer

Given v1=20km/hr.....v2=30km/hr....->> Average speed (v)=2v1v2/v1+v2 v=24km/hrThis might be useful for you: 'Motion - Motion in a Straight Line, Class 11, Physics '

Motion - Motion in a Straight Line, Class 11, Physics

https://edurev.in/studytube/motion-motion-in-a-straight-line--class-11--physic/086ff6cd-37b4-4ee9-b146-8de262907385_t

to know more refer the doc...

Answer

Answer

Use total distance covered by total time taken .. B is ryt

Answer

To find the average speed of the car for the whole journey, we can use the formula:

Average speed = Total distance / Total time

Let's assume the distance from A to B is 'd' kilometers. Since the car travels from A to B at a speed of 20 km/h, the time taken to cover this distance is:

Time taken to go from A to B = d / 20

Similarly, when the car returns from B to A at a speed of 30 km/h, the time taken is:

Time taken to return from B to A = d / 30

Now, to find the total time taken for the whole journey, we need to add the time taken to go from A to B and the time taken to return from B to A:

Total time = (d / 20) + (d / 30)

Simplifying this expression, we get:

Total time = (3d + 2d) / 60
Total time = 5d / 60
Total time = d / 12

Since we know that Average speed = Total distance / Total time, we can substitute the value of Total time in the above equation:

Average speed = d / (d / 12)
Average speed = d * (12 / d)
Average speed = 12 km/h

Therefore, the average speed of the car for the whole journey is 12 km/h.

However, none of the given options match this answer. So, it seems there is an error in the question or answer choices provided.

Answer

(v1+v2)/2

Similar Class 11 Doubts

Car a and b travel 100km journey together. Car a travels with the uniform speed of 40 km/h. But after half an hour it stops for 15 min due to some problem and when it moves its speed remains 50 km /h ?

a person cycles from home to college situated at distance of 1.4kms finding college closed he returns back home. he takes a total of 1hr for his journey. find the average speed ( I'm m/s)

On a 60 km straight road , a bus travels the rest 30 km with a uniform speed of 30km/h . How fast must the bus travels the next 30 km as to have average speed of 40 km/h for the entire trip?

A bus starts from town A and reaches town B with speed of 40 km/hr. It returns town A with speed 60 km/hr. The average velocity of the bus is?

If car travels one fourth of the distance at a speed of 10 metre per second and remaining distance at a speed of 15 metre per second what is the average speed of car.?

Top Courses for Class 11View all

Chemistry Class 11

CUET Mock Test: Humanities Subjects 2025

English Class 11

Mathematics (Maths) Class 11

Psychology Practice Tests: CUET Preparation

Top Courses for Class 11

Top Courses for Class 11

Related Content

Schools

Competitive Examinations

Quick Access Links

Technical Exams