Question

a car covers first 50 kilometre at a uniform velocity of 45 km per hour and next 50 km with uniform speed of 90 km per hour find the average speed​

Answer 1

First find time of each part .

T=D/V

T1=50/45 =10/9

T2= 50/90=5/9

total distance

=(50+50) =¹00

Total time (10/9 + 5/9)

= 15/9 = 5/3

AV= 100/ 5/3

=100*3/5. =20*3 = 60km/hr

Answer 2

$\huge\star\:\:{\orange{\underline{\red{\mathbf{Answer}}}}}$

$\sf\huge\orange{Case\:one}$

$\Longrightarrow$ The distance covered here = 50 km

$\Longrightarrow$ The velocity / speed = 45 km / h

$\Longrightarrow$ The time taken = $\huge\frac{Distance}{Speed}$

$\Longrightarrow\:\dfrac{50}{45}$

$\Longrightarrow\:\dfrac{10}{9}$ hours

$\sf\huge\purple{Case\:second}$

$\Longrightarrow$ The distance covered here = 50 km

$\Longrightarrow$ The velocity / speed = 90 km / h

$\Longrightarrow$ The time taken = $\huge\frac{Distance}{Speed}$

$\Longrightarrow\:\dfrac{50}{90}$

$\Longrightarrow\:\dfrac{5}{9}$ hours

Average velocity = $\frac{Total\: distance\:covered}{Total\:Time\:Taken}$

$\implies\:\frac{50\:+\:50}{\frac{10}{9}\:+\:\frac{5}{9}}$

$\implies\:\frac{100}{\frac{15}{9}}$

$\implies\:\frac{100\:\times\:9}{15}$

$\implies$ 60 km / h