Question

② Car travels a distance of 900km with an
average speed of 45km/hr. How much time does
it take to cover the distance?​

Answer 1

Answer:

20 hours

And please mark me brainleast.

Answer 2

Finding according to ques.!

Proper question: Car travels a distance of 900 km with an average speed of 45 km hr. How much time does it take to cover the distance?

Provided that:

• Distance = 900 km
• Average speed = 45 km/h

To calculate:

• The time taken

Solution:

• The time taken = 20 hours

Using concept:

• Average speed formula

Using formula:

• ${\small{\underline{\boxed{\sf{v \: = \dfrac{s}{t}}}}}}$

Where, v denotes average speed, s denotes distance, t denotes time taken

Required solution:

$:\implies \sf Average \: speed \: = \dfrac{Total \: distance \: travelled}{Total \: time \: taken} \\ \\ :\implies \sf v \: = \dfrac{s}{t} \\ \\ :\implies \sf 45 = \dfrac{900}{t} \\ \\ :\implies \sf t = \: \dfrac{900}{45} \\ \\ :\implies \sf t \: = \cancel{\dfrac{900}{45}} \\ \\ :\implies \sf t \: = 20 \: hr \\ \\ :\implies \sf Time \: taken \: = 20 \: hours$

__________________________

Finding according to SI unit!

Proper question: Car travels a distance of 900 km with an average speed of 45 km hr. How much time does it take to cover the distance?

Provided that:

• Distance = 900 km
• Average speed = 45 km/h

To calculate:

• The time taken

Solution:

• The time taken = 20 hours

Using concept:

• Average speed formula
• Formula to convert km into m
• Formula to convert km/h into m/s

Using formula:

• ${\small{\underline{\boxed{\sf{v \: = \dfrac{s}{t}}}}}}$

Where, v denotes average speed, s denotes distance, t denotes time taken

• ${\small{\underline{\boxed{\sf{1 \: km \: = 1000 \: m}}}}}$

Knowledge required:

• SI unit of distance is m
• SI unit of average speed is m/s
• SI unit of time is seconds

Required solution:

~ Firstly let us convert km into m

$:\implies \sf 1 \: km \: = 1000 \: m \\ \\ :\implies \sf 900 \: km \: = 1000 \times 900 \: metres \\ \\ :\implies \sf 900 \: km \: = 9,00,000 \: metres$

~ Now let's convert km/h into m/s

$:\implies \sf 45 \times \dfrac{5}{18} \\ \\ :\implies \sf \cancel{45} \times \dfrac{5}{\cancel{18}} \\ \\ :\implies \sf 2.5 \times 5 \\ \\ :\implies \sf 12.5 \: m/s \\ \\ {\pmb{\sf{Henceforth, \: converted!!}}}$

~ Now let's calculate average speed by using formula!

$:\implies \sf Average \: speed \: = \dfrac{Total \: distance \: travelled}{Total \: time \: taken} \\ \\ :\implies \sf v \: = \dfrac{s}{t} \\ \\ :\implies \sf 12.5 = \dfrac{9,00,000}{t} \\ \\ :\implies \sf t = \dfrac{9,00,000}{12.5} \\ \\ :\implies \sf t \: = 72000 \: second \\ \\ :\implies \sf Time \: = 72000 \: second$