Question

Q.3 Class Test 2 Work Power & Energy PHYSICS NMDCAT How much work must be done by a force on a 50 kg body in order to accelerate it from rest to 20 m/s in 10 sec. A) 2x 103 C) 103j B) 10 4 j D) 4x10 j STAR INSTITUTE LAHORE​

Answer 1

Answer:

• The work done by the force is 10⁴ J

Explanation:

Given, Mass (M) = 50 Kg

          Initial velocity (u) = 0 m/s

          Final velocity (v) = 20 m/s

          Time taken (t) = 10 sec

From work energy theorem we know that,

$\longrightarrow\sf W=\dfrac{1}{2}\;.\;m\bigg(v^{2}-u^{2}\bigg)$

Substituting the values,

$\\\\\\\\\longrightarrow\sf W=\dfrac{1}{2}\times 50 \times \bigg((20)^{2}-(0)^{2}\bigg) \\\\\\\\\longrightarrow\sf W=\dfrac{1}{2}\times 50 \times 400 \\\\\\\\\longrightarrow\sf W=50 \times 200\\\\\\\\\longrightarrow\sf W= 10000\\\\\\\\\longrightarrow\sf W=10^{4}\;J$

∴ The work done by the force is 10⁴ J.

Answer 2

⇝Given :-

• Mass of the body is 50 kg.
• Initial Velocity = 0 (as it starts from rest)
• Final Velocity = 20 m/s
• Time = 10s

⇝To Find :-

• Work Done = ?

⇝Solution :-

${\red{✧}}{\underline{\bf{ We \: know \: that :}}}$

${\large{\red{\bigstar \: \: {\blue{\underbrace{\underline{\orange{\bf{W = \frac{1}{2} \times M(V² - U²)}}}}}}}}}$

${\red{✧}}{\underline{\bf{ Work\: done:}}}$

${\large{:{\longmapsto{\bf{W = \frac{1}{2} \times m( {v}^{2} - {u}^{2} ) }}}}}$

${\large{:{\longmapsto{\bf{ \: \: \: \: \: \: \: \: \: \: \: \: \frac{1}{2} \times 50( {20}^{2} - {0}^{2} ) }}}}}$

${\large{:{\longmapsto{\bf{ \: \: \: \: \: \: \: \: \: \: \: \: \: \frac{1}{2} \times 50( 400 - {0}) }}}}}$

${\large{:{\longmapsto{\bf{ \: \: \: \: \: \: \: \: \: \: \: \: \: \frac{1}{2} \times 50 \times 400 }}}}}$

${\large{:{\longmapsto{\bf{ \: \: \: \: \: \: \: \: \: \: \: \: \: \frac{1}{\cancel{2}} \times {\cancel{20000 }}}}}}}$

${\large{:{\longmapsto{\bf{ \: \: \: \: \: \: \: \: \: \: \: \: \: 1 \times 10000}}}}}$

${\large{:{\longmapsto{\bf{ \: \: \: \: \: \: \: \: \: \: \: \: \: 10000 \: j}}}}}$

${\large{\purple{:{\longmapsto{\underline{\overline{\boxed{\bf{ {10}^{4} \: J}}}}}}}}}$

${\red{✧}}{\underline{\bf{Therefore :}}}$

${\large{\red{\underline{\green{\underline{\orange{\mathfrak{Work \: Done = {10}^{4} \: Joules}}}}}}}}$

▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃