Question

A body moving with an initial velocity of 5 m/s accelerates at 2 m/s?. Its velocity after 10 s is (a)20 m/s (b)25 m/s (c) 5 m/s (d) 22.5 m/s​

Answer 1

Explanation:

v=u+at

v=5+(2×10)

v=5+20

v=25 m/s

option (b)

Answer 2

Answer:

Gɪᴠᴇɴ :

• ➛ Initial velocity = 5 m/s.
• ➛ Acceleration = 2 m/s².

$\begin{gathered}\end{gathered}$

Tᴏ Fɪɴᴅ :

• ➛ Velocity after 10 seconds.

$\begin{gathered}\end{gathered}$

Cᴏɴᴄᴇᴘᴛ :

↝ Here the concept of 1st equation of motion has been used. Here we are given that the initial velocity of the body is 5m/s. The time taken is 10 sec and the acceleration is 2m/s². Now, as per the situation we need to apply the first equation of motion.

$\begin{gathered}\end{gathered}$

Usɪɴɢ Fᴏʀᴍᴜʟᴀ :

$\star$ First equation of motion :

${\longrightarrow{\underline{\boxed{\pmb{\sf{v = u + at}}}}}}$

Where, 

• ↠ v = final velocity
• ↠ u = initial velocity
• ↠ a = acceleration 
• ↠ t = time taken.

$\begin{gathered}\end{gathered}$

Sᴏʟᴜᴛɪᴏɴ :

☼ Finding the final velocity by substituting the values in the formula :-

${\longrightarrow{\sf{v = u + at}}}$

${\longrightarrow{\sf{v = 5 + (2 \times 10)}}}$

${\longrightarrow{\sf{v = 5 + (20)}}}$

${\longrightarrow{\sf{v = 5 + 20}}}$

${\longrightarrow{\sf{v = 25 \: m/s}}}$

$\bigstar \: {\underline{\boxed{\sf{Final \: velocity = 25 \: m/s}}}}$

∴ The option (b)25 m/s is the correct answer.

$\begin{gathered}\end{gathered}$

Lᴇᴀʀɴ Mᴏʀᴇ :

$\star$ Velocity

${\longrightarrow{\small{\underline{\boxed{\bf{v = u + at}}}}}}$

$\star$ Displacement with positive accelerations

${\longrightarrow{\small{\underline{\boxed{\bf{s= ut + \dfrac{1}{2}{at}^{2}}}}}}}$

$\star$ Displacement with negative acceleration

${\longrightarrow{\small{\underline{\boxed{\bf{s= ut - \dfrac{1}{2}{at}^{2}}}}}}}$

$\star$ Displacement knowing initial and final speeds

${\longrightarrow{\small{\underline{\boxed{\bf{s= \dfrac{1}{2}\big(u + v \big)t}}}}}}$

$\star$ Velocity squared

${\longrightarrow{\small{\underline{\boxed{\bf{{v}^{2} = {u}^{2} + 2as}}}}}}$

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