Question

A block weighing 20 N is lifted 6 m vertically upward. Calculate the potential energy stored in it.
1 3.33 J
2 124 J
3 72 J
4 120 J

Answer 1

$\bigstar$ Given

A block weighing 20 N is lifted 6 m vertically upward

$\bigstar$ To Find

Potential energy stored in it

$\bigstar$ Solution

We know that

$\blue{\rm \longrightarrow F=m \times g}$

$\green{\rm \longrightarrow U=m \times g \times h}$

Hence

$\red{\rm \longrightarrow U=F \times h}$

Here

• U = Potential Energy
• F = Force
• h = Height

Units

• U = Joule (J)
• F = Newton (N)
• h = metre (m)

According to the question

We are asked to find potential energy stored in it

Therefore

We must find "U"

Given that

A block weighing 20 N is lifted 6 m vertically upward

Hence

• F = 20 N
• h = 6 m

Substituting the values

We get

$\orange{\rm \longrightarrow U=20 \times 6 \ J}$

Therefore

$\pink{\rm \longrightarrow U=120 \ J}$

Hence

Potential energy stored in it = 120 J

Therefore

$\checkmark$ Option (4) is correct

Answer 2

$\Large\bf{\color{indigo}GiVeN,}$

• Weight of a block is 20N.

• The block is lifted 6m vertically upward.

$\Large\bf{\color{cyan}To\:FiNd,}$

• The potential energy stored in the block.

$\Large\bf{\color{coral}CaLcUlAtIoN,}$

Weight Of A Body ;-

• The force exerted on a body by gravity, is known as Weight of a body.

☆ The expression of weight of a body is

$\orange\bigstar\:\:\bf{\color{olive}Weight\:(W)\:=\:mg\:}--(1)$

$\bf\pink{Where,}$

• m = mass of a body

• g = gravitational acceleration

$\bf\red{We\:know\:that,}$

$\green\bigstar\:\:\bf\blue{Potential\:Energy\:=\:mgh\:}$

$\bf\pink{Where,}$

• h = Height

➡ From equation(1) using the expression of weight in the above equation

$:\implies\:\:\bf{Potential\:Energy\:=\:Weight\times{Height}\:}$

$:\implies\:\:\bf{Potential\:Energy\:=\:20\:N\times{6\:m}\:}$

$:\implies\:\:\bf{Potential\:Energy\:=\:120\:N.m\:}$

$:\implies\:\:\bf\purple{Potential\:Energy\:=\:120\:J\:}$

$\Large\bold\therefore$ The potential energy stored in the block is 120 J.

$\red\bigstar\:\:{\boxed{\boxed{\green{\bf{Correct\:Option\:\longrightarrow\:(4)\:120\:J\:}}}}}$