Question

A man lifts a brick of mass 5 kg from the floor to a shelf 2 meters high. how much work is done ?​

Answer 1

Given

A man lifts a brick of mass 5 kg from the floor to a shelf 2 meters high

To Find

Work done

Solution

We know that

$\red{\sf \longrightarrow W=mgh}$

Here

• W = Work done
• m = Mass
• g = Acceleration of gravity
• h = Height

Units

• W = Joule (J)
• m = kilogram (kg)
• g = metre/square second (m/s²)
• h = metre (m)

According to the question

We are asked to find the work done

Therefore

We must find "W"

Given that

A man lifts a brick of mass 5 kg from the floor to a shelf 2 meters high

Hence

• m = 5 kg
• h = 2 m

We know that

• g = 9.8 m/s²

Substituting the values

We get

$\blue{\sf \longrightarrow W=5 \times 9.8 \times 2 \ J}$

$\green{\sf \longrightarrow W=49 \times 2 \ J}$

Therefore

$\pink{\sf \longrightarrow W=98 \ J}$

Hence

Work done = 98 J

Answer 2

$\; \; \; \; \; \; \; \; \;\orange \bigstar{\Large{\bold{\bf{Required \; Solution}}}}\orange \bigstar$

${\large{\bold{\rm{\underline{Given \; that}}}}}\red \bigstar$

✠ Mass of brick = 5 kg.

✠ Height = 2 metres

${\large{\bold{\rm{\underline{To \; find}}}}}\red \bigstar$

✠ Work done.

${\large{\bold{\rm{\underline{Solution}}}}}\green \bigstar$

✠ Work done = 98 J

${\large{\bold{\rm{\underline{Using \; concept}}}}}\pink \bigstar$

✠ Formula to find work done.

${\large{\bold{\rm{\underline{Using \; formula}}}}}\pink \bigstar$

✠ W = mgh

${\large{\bold{\rm{\underline{Full \; Solution}}}}}\green \bigstar$

~ Let us use formula to find work done and let's put the values,

⇝ W = mgh

$\; \; \; \; \; \; \; \; \; \; \; \; \;{\sf{Where,}}$

✨ W denotes work done

✨ m denotes mass

✨ g denotes acceleration due to gravity

✨ h denotes height

$\; \; \; \; \; \; \; \; \; \; \; \; \;{\sf{Here,}}$

✨ Work done is ?

✨ m is 5 kg

✨ Value of g is 9.8 m/s²

✨ h is 2 metres

⇝ W = 5(9.8)(2)

⇝ W = 5 × 9.8 × 2

⇝ W = 10 × 9.8

⇝ W = 98 Joules

$\; \; \; \; \;{\boxed{\boxed{\bold{\bf{98 \: J \: is \: work \: done}}}}}$

$\; \; \; \; \; \; \; \; \;\orange \bigstar{\Large{\bold{\bf{Additional \; information}}}}\orange \bigstar$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Number \: of \: SI \: units \: are \: 7}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Ampere \: is \: the \: unit \: of \: current \: electricity}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto SI \: unit \: of \: Young's \: modulus \: of \: elasticity \: is \: Newton/m^{2}}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto SI \: unit \: of \: pressure \: is \: Pascal}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Curie \: is \: the \: unit \: of \: radio \: activity}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Decibel \: is \: the \: unit \: of \: intensity \: of \: sound}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto SI \: unit \: of \: electric \: charge \: is \: coulomb}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto SI \: unit \: of \: resistance \: is \: ohm}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto SI \: unit \: of \: acceleration \: is \: ms^{-2}}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Kinetic \: energy \: is \: given \: by \: \dfrac{1}{2}mv^{2}}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Value \: of \: G \: is \: 6.673 \times 10^{-11}Nm^{2}kg{-3}}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Dimensional \: formula \: for \: universal \: gravitational \: constant \: is \: M^{-1} L^{3} T^{-2}}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto The \: unit \: of \: force \: constant \: k \: of \: a \: spring \: is \: \dfrac{N}{m}}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Sir \: Cavendish \: was \: the \: first \: to \: gave \: value \: of \: G \: experimentally}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto The \: Young's \: modulus \: for \: perfect \: rigid \: body \: is \: infinite}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Density \: is \: the \: ratio \: of \: \dfrac{Volume}{Mass}}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Maxwell \: is \: unit \: of \: magnetic \: flux}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto SI \: unit \: of \: magnetic \: flux \: is \: Weber}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto SI \: unit \: of \: surface \: tension \: is \: \dfrac{N}{m}}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto SI \: unit \: of \: mechanical \: power \: is \: Watt}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto 1 \: horsepower \: = \: approx \: 746 \: watts}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto Momentum \: is \: measured \: as \: the \: product \: of \: Mass \: and \: velocity}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto \pi \: 'pi' \: is \: calculated \: by \: Aryabhatta}}}$

$\; \; \; \; \; \; \;{\sf{\bold{\leadsto One \: J \: = \: 0.24 \: cal}}}$