Question

15 An object travels 25 m in 4 s and then
another 15 min 1 s, what is the average speed of
the object?
(a) 5 ms
(d) 8 ms
(b) 6 ms -1
​

Answer 1

$\dag\:\underline{\sf AnsWer :}$

We are given one object that travels 25 m in 4 second at the starting of it's journey and at the end the object travels 15 m in 1 second and we are asked to find the Average Speed of the object.

• To calculate the Average Speed of the given object we have to use the given below formula :

$\ddag\:\: \sf Average \: Speed = \dfrac{Total \: distance \: travelled \: by \: the \: object}{Total \: Time \: taken \: by \: the \: object}$

First we need to calculate the total distance travelled by the object and then we have to find the total time taken by the object after finding this two things we can calculate the Average Speed of the object.

$\bigstar\:\underline{\textbf{ Total distance travelled by the object : }}$

$:\implies\sf Total \: Distance \: travelled = Distance \: travelled \: at \: starting \: of \: the \: journey + Distance \: travelled \: till \: the \: end \: of \: the \: journey$

$:\implies\sf Total \: Distance \: travelled = 25+ 15$

$:\implies \underline{ \boxed{\sf Total \: Distance \: travelled = 40 \: m}}$

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$\bigstar\:\underline{\textbf{ Total time taken by the object : }}$

$\dashrightarrow\:\:\sf Total \: Time \: taken = Time \: taken \: at \: the \: starting \: of \: the \: journey + Time \: taken \: till \: end \: of \: the \: journey$

$\dashrightarrow\:\:\sf Total \: Time \: taken =4 + 1$

$\dashrightarrow\:\: \underline{ \boxed{\sf Total \: Time \: taken =5 \: second}}$

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$\qquad \quad\bigstar\:\underline{\textbf{Average Speed : }}$

$\longrightarrow\:\:\sf Average \: Speed = \dfrac{Total \: distance \: travelled \: by \: the \: object}{Total \: Time \: taken \: by \: the \: object}$

$\longrightarrow\:\:\sf Average \: Speed = \dfrac{40}{5}$

$\longrightarrow\:\: \underline{ \boxed{\sf Average \: Speed = 8 \: ms^{ - 1} }}$

Hence,the average speed of the object is (D) 8 m/s.

Answer 2

Appropriate Question:-

An object travels 25 m in 4 s and then another 15 m 1 s, what is the average speed of the object?

(a) 5 m/s

(d) 8 m/s

(b) 6 m/s

$\huge\bf{\orange{\underline{\underline{\mathcal{AnSwer}}}}}$

Concept:-

• in the question we are asked to find the Average speed of an object which travels 25m in 4 sec. and then 15 m in another 1 sec.

Formula to be used:-

$\longrightarrow$ $\underline\pink{\boxed{\bf Average\:Speed = \dfrac{Total\:distance\: travelled}{ Total\:time\:taken}}}$

• Let's calculate the Total Distance by summing up the distance that was initially travelled (25m) and the one travelled later (15m)

$\longrightarrow$ ${\boxed{\sf Total\:distance = 25+15}}$

:$\implies$ $\underline\green{\boxed{\sf Total\:distance = 40m}}$

• Now, let's calculate the total time taken by adding up the time taken initially and the one afterwards.

$\longrightarrow$ ${\boxed{\sf Total\:Time = 4+1}}$

:$\implies$ $\underline\purple{\boxed{\sf Total\:Time = 5 sec.}}$

Now, the Average speed will be calculated:-

$\dashrightarrow$ $\pink{\boxed{\sf Average\:speed = \cancel\dfrac{40m}{5sec}}}$

:$\implies$ $\underline\blue{\boxed{\sf Average\:speed = 8 m/s}}$

Hence, 8m/s is the required Average speed

So, (D) option is right

Note:- Always keep an eye over the units

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