Question

Calculate the work done by a student
in a book of 0.2 kg from the table and keeping it in shelf of 2meters of height ​

Answer 1

Question :

Calculate the work done by a student  in a book of 0.2 kg from the table and keeping it in shelf of 2 meters of height ​?

Solution :

★ ═════════════════════ ★

Gravitational Potential Energy (P) :

         It is the energy stored in an object due to it's height above the earth .

➠ P = mgH

where ,

• m denotes mass of the object
• g denotes acceleration due to gravity
• H denotes height of the object from the earth's surface

★ ═════════════════════ ★

Work (W) : It is defined as product of component of force in the direction of displacement .

Here , work done to move an object from ground to a shelf of 2 m is equals to gravitational potential energy .

Note : Units of both work done and potential energy are equal ( Joules )

Mass of the book (m) = 0.2 kg

Height (H) = 2 m

Acceleration due to gravity (g) = 9.8 m/s²

Work done (W) = ? J

➠ W = F × H $\red{\bigstar}$

➠ W = (ma) × H   [ ∵ F = ma ]

➠ W = m × g × H  $\green{\bigstar}$

➠ W = 0.2 × 9.8 × 2

➠ W = 3.92 J  $\pink{\bigstar}$

Answer 2

Gɪᴠᴇɴ :

• Mass of a book is 0.2 kg.

$:\longrightarrow\:\:\bf{Mass\:(m)\:=\:0.2\:kg\:}$

• Height to keep it in shelf is 2 m.

$:\longrightarrow\:\:\bf{Height\:(h)\:=\:2\:m\:}$

Tᴏ Fɪɴᴅ :

• Work done by student.

Cᴀʟᴄᴜʟᴀᴛɪᴏɴ :

➣ Force due to gravity acts in downward direction.

➣ It is denoted as 'g'.

➣ It's value is,

• g = 9.8 m/s²

Wᴇ ᴋɴᴏᴡ ᴛʜᴀᴛ,

➛ Work done by force due to gravity is given by,

$\red\bigstar\:\:{\underline{\orange{\boxed{\bf{\green{W\:=\:m\:g\:h}}}}}}$

Wʜᴇʀᴇ,

• W = Work done

• m = Mass of body

• g = Acceleration due to gravity

• h = height

$:\implies\:\:\sf{W\:=\:0.2\times{9.8}\times{2}}$

$:\implies\:\:\sf\pink{W\:=\:3.92\:J}$

$\Large\bf\purple{Therefore,}$

Work done by the student is 3.92 J.