Question

2.
Determine the time taken when:
(a) Distance = 7150 km, speed = 780 km/h
2
(b) Distance = 8 m, speed = 85 cm/sec
5
(c) Distance = 27 km, speed = 45 km/h​

Answer 1

★ Concept :-

• Speed is how fast/slow the vehicle is moving in a certain period of time.

• Distance is km/m the vehicle has travelled.

• Time is the time taken to cover the distance.

★ We know that ,

• $\boxed{ \underline{ \sf \red{Time = { \frac{ Distance}{Speed } }}} }$

★ (a) Distance = 7150 km, speed = 780 km/h :

$\sf \implies Time = \dfrac{7150}{780}$

$\sf \implies \dfrac{56}{6} \: or \: 9.16$

Hence, If Distance = 7150 km, speed = 780 km/h Time will be 9.17 hours.

★ (b) Distance = 8 m, speed = 85 cm/sec :

• Converting 8m into cm as speed is given in cm. 8m = 800cm.
• Now, Apply the formula.

$\sf \implies Time = \dfrac{800}{85}$

$\sf \implies 9.41 \: seconds$

Hence, If Distance = 8 m, speed = 85 cm/sec. Time will be 9.41 seconds.

★ (c) Distance = 27 km, speed = 45 km/h :

$\sf \implies Time = \dfrac{27}{45}$

$\sf \implies 0.6 \: hours.$

Hence, If Distance = 27 km, speed = 45 km/h. Time will be 0.6 hours.

Answer 2

$\boxed{\huge{\bf{\star{Correct\:question \:-:}}}}$

• Find the time taken when -:

• (a) Distance = 7150 km, Speed = 780 km/h

• (b) Distance = 8 m, Speed = 85 cm/sec

• (c) Distance = 27 km, Speed = 45 km/h

AnswEr-:

• $\underline{\boxed{\sf{\large {A) \:=\:Time\:Taken\:=\:9.16 \:hours}}}}$
• $\underline{\boxed{\sf{\large {B)\:=\:Time\:Taken\:=\:9.14 \:seconds}}}}$

• $\underline {\boxed{\sf{\large {C)\:=\:Time\:Taken\:=\:0.6 \:hours}}}}$

Explanation-:

• $\frak{Given \:\: -:} \begin{cases} \sf{ (a) \:Distance\: =\: 7150 \:km\:, Speed \:= \:780 km/h } & \\\\ \sf{ (b)\: Distance\: =\: 8\: m\:, Speed \:= 85 \:cm/sec} & \\\\ \sf{ (c)\: Distance\: =\: 27\: m\:, Speed \:= 45 \:km/hr}\end{cases}$

• $\frak{To \:Find\: -:} \begin{cases} \sf{ The\:Time\:Taken\:in\:each\:case\:}\end{cases}$

$\dag{\underline {\sf{\large { As\:we\:know\:that\: -: }}}}$

• $\underline{\boxed{\star{\sf{\red{Time\:Taken\:= \: \dfrac{Distance}{Time}}}}}}$

_________________________________________________

$\star{\bigstar {\sf{\large { Solution \:of\:A-: }}}}$

• $\underline{\boxed{\star{\sf{\blue{Time\:Taken\:= \: \dfrac{Distance}{Time}\:=[ Formula\:1]}}}}}$

• $\frak{ \:Here\: -:} \begin{cases} \sf{ (a) \:Distance\: =\: 7150 \:km\:, Speed \:= \:780 km/h\:}\end{cases}$

• $\star{\underline {\sf{\large {Putting\:known\:values\:in\:Formula\:1-: }}}}$

• $\longrightarrow{\sf{\large {Time\:Taken\:=\:\dfrac{7150}{780}}}}$

• $\longrightarrow{\sf{\large {Time\:Taken\:=\:\dfrac{56}{6}}}}$

• $\longrightarrow{\sf{\large {Time\:Taken\:=\:9.16 \:hours}}}$

$\star{\bigstar {\sf{\large { Therefore \:-: }}}}$

• $\boxed{\sf{\large {Time\:Taken\:=\:9.16 \:hours}}}$

_______________________________________________

$\star{\bigstar {\sf{\large { Solution \:of\:B-: }}}}$

• $\underline{\boxed{\star{\sf{\blue{Time\:Taken\:= \: \dfrac{Distance}{Time}\:=[ Formula\:1]}}}}}$

• $\frak{ \:Here\: -:} \begin{cases} \sf{ (b) \:Distance\: =\: 8\:m\:or\:800cm\:[1m\:=100cm]\:, Speed \:= \:85cm/sec\:}\end{cases}$

• $\star{\underline {\sf{\large {Putting\:known\:values\:in\:Formula\:1-: }}}}$

• $\longrightarrow{\sf{\large {Time\:Taken\:=\:\dfrac{800}{85}}}}$

• $\longrightarrow{\sf{\large {Time\:Taken\:=\:\dfrac{160}{17}}}}$

• $\longrightarrow{\sf{\large {Time\:Taken\:=\: 9.41\:seconds}}}$

$\star{\bigstar {\sf{\large { Therefore \:-: }}}}$

• $\boxed{\sf{\large {Time\:Taken\:=\:9.14 \:seconds}}}$

_________________________________________________

$\star{\bigstar {\sf{\large { Solution \:of\:C-: }}}}$

• $\underline{\boxed{\star{\sf{\blue{Time\:Taken\:= \: \dfrac{Distance}{Time}\:=[ Formula\:1]}}}}}$

• $\frak{ \:Here\: -:} \begin{cases} \sf{ (c) \:Distance\: =\: 27\:km\:, Speed \:= \:45 km/h\:}\end{cases}$

• $\star{\underline {\sf{\large {Putting\:known\:values\:in\:Formula\:1-: }}}}$

• $\longrightarrow{\sf{\large {Time\:Taken\:=\:\dfrac{27}{45}}}}$

• $\longrightarrow{\sf{\large {Time\:Taken\:=\:0.6 \:hours}}}$

$\star{\bigstar {\sf{\large { Therefore \:-: }}}}$

• $\boxed{\sf{\large {Time\:Taken\:=\:0.6 \:hours}}}$

____________________________________________________

$\dag{\underline {\sf{\large { Hence\: -: }}}}$

• $\underline{\boxed{\sf{\large {A) \:=\:Time\:Taken\:=\:9.16 \:hours}}}}$

• $\underline{\boxed{\sf{\large {B)\:=\:Time\:Taken\:=\:9.14 \:seconds}}}}$

• $\underline {\boxed{\sf{\large {C)\:=\:Time\:Taken\:=\:0.6 \:hours}}}}$

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