Question

Car travels 10 kilometre distance at the speed of 60 km per hour and returns with a speed of 40 kilometre per hour calculate average speed

Answer 1

Given :

• Distance travelled by car (s) = 10km
• Car initially travel with the speed of (u) = 60km/h and return with the speed of (v) = 40km/h

To Find :

• Average Speed

Formula Used :

$\bullet\underline{\boxed{\sf Average \; Speed =\dfrac{Total \: Distance}{Total \; Time }}}$

Solution :

Time = Distance/Speed

t1 = 10/60

t1 = 1/6

t2 = 10/40

t2 = 1/4

⟹ T = t1 + t2

⟹ T = 1/6 + 1/4

⟹ T = 10/24 h

$\implies{\sf v_{av}=\dfrac{s}{T}}$

$\implies{\sf v_{av}= \dfrac{10}{\dfrac{10}{24}}}$

$\implies{\sf v_{av}=24\: km/h}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀OR

In m/s

⟹ 24 × 5/18

⟹ 6.6 m/s

Answer :

Average speed of car is 24 km/h or 6.6m/s

Answer 2

✬ Average Speed = 48 km/h ✬

Explanation:

Given:

• Total distance (s) covered by car is 10 km.
• Speed of car while going is 60 km/h.
• Speed of car while returning is 40 km/h.

To Find:

• What is the average speed of car?

Formula to be used:

• Time = Distance/Speed
• Average Speed = Total distance/Total time

Solution: In case 1 , when car is going :-

• Distance travelled = 10 km
• Speed = 60 km/h
• Time = ?

$\implies{\rm }$ Time = 10/60 h

$\implies{\rm }$ Time = 1/6 hours.....(1)

• In case 2 , when car is returning :-

• Distance covered = 10 km
• Speed = 40 km/h
• Time = ?

$\implies{\rm }$ Time = 10/40 h

$\implies{\rm }$ Time = 1/4 hours.....(2)

∴ Total distance = 10 + 10 = 20 km and

Total time = 1/6 + 1/4 = (2 + 3/12) = 5/12 hours

Therefore, Average Speed :-

$\implies{\rm }$ Average Speed = 20/5/12

$\implies{\rm }$ 20 $\times$ 12/5

$\implies{\rm }$ 240/5

$\implies{\rm }$ 48 km/hr

Hence, The average speed of car is 48 km/h.