Question

10. A car moves with a speed of 30 km/h for half an hour, 25 km/h for one hour and 40 km/h for two hours. calculate the average speed of the car.
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Answer 1

ɢɪᴠᴇɴ :-

A car moves with a speed of 30 km/h for half an hour, 25 km/h for one hour and 40 km/h for two hours.

ᴛᴏ ғɪɴᴅ :-

• Average speed

Sᴏʟᴜᴛɪᴏɴ :-

We know that,

➪ Distance = Speed × Time

So,

Case - 1

• Speed = 30 km/h
• Time = 1/2 hr or 0.5 h
• Distance = 30 × 1/2 = 15 km

Case - 2

• Speed = 25 km/h
• Time = 1 hr
• Distance = 25 × 1 = 25 km

Case - 3

• Speed = 40 km/hr
• Time = 2 hrs
• Distance = 40 × 2 = 80 km

Now,

We know that,

$\implies \sf \: Average \: Speed \: = \frac{Total \: Distance \: Covered}{Total \: Time \: Taken} \\ \\ \\ \\ \implies \tt \: A .\: S = \frac{ 15 + 25 + 80}{0.5 + 1 + 2} \\ \\ \\ \\ \implies \tt \: A. \: S = \frac{120}{3.5} \\ \\ \\ \\ \implies \tt \: A .\: S \: = 34.28 {kmh}^{ - 1}$

Hence,

• Average speed (A. S.) = 34.28 ≈ 34.3 km/h

Answer 2

${ \huge{ \bold{ \underline{ \underline{ \purple{Question:-}}}}}}$

A car moves with a speed of 30 km/h for half an hour, 25 km/h for one hour and 40 km/h for two hours. calculate the average speed of the car.

_______________

${ \huge{ \bold{ \underline{ \underline{ \pink{Answer:-}}}}}}$

✒Given : -

• 30 km/h for half an hour, 25 km/h for one hour and 40 km/h for two hours.

✒To Find : -

• Average Speed of the car = ?

★ In First Case ★

⠀⠀⠀⠀⠀→ Time = 1/2 = 0.5 hr.

⠀⠀⠀⠀⠀ → Speed = 30 km/hr.

⠀⠀⠀⠀⠀→ Distance = 25 × 1 = ⠀⠀⠀⠀⠀ 25km

★ In Second Case ★

⠀⠀⠀⠀⠀→ Time = 1 hr.

⠀⠀⠀⠀⠀→Speed = 25 km/hr.

⠀⠀⠀⠀⠀→ Distance = 40 × 2 = ⠀⠀⠀⠀⠀ 80km

★ In Third Case ★

⠀⠀⠀⠀⠀→Time = 2 hr.

⠀⠀⠀⠀⠀→ Speed = 40 km/hr.

⠀⠀⠀⠀⠀→ Distance = 40 × 2 = ⠀⠀⠀⠀⠀ 80km

✒Formula Used : -

$\leadsto\sf{{ \small{ \bold{ \bold{ \bold{ \red{Average\:Speed=\dfrac{Total\:Distance\:Travelled}{Total\:Time\:Taken}}}}}}}}$

✒On Substituting Values : -

$\dashrightarrow\sf{\dfrac{15+25+80}{0.5+1+2}}$

$\dashrightarrow\sf{\cancel\dfrac{120}{3.5}}$

$\leadsto\sf{{ \large{ \boxed{ \bold{ \bold{ \green{A.S.=34.28{km/h}^{-1}}}}}}}}$

✒Therefore , Average Speed of car is 34.3 km/h ..