Question

A body of mass 2 kg is at rest 500 joule work
is done on the body to raise it to 10 meters
what is the speed
​

Answer 1

Given :-

• Mass of the body = 2k

• Work done by body = 500 J

• Initial velocity = 0 m/s

• Displacement = 10 m

To Find :-

• Speed of the body

Solution :-

Firstly we have to find Force of the body

$\longrightarrow \: \bf Work = Force\times Displacement \\ \\ \longrightarrow \: \sf 500 = F\times 10 \\ \\\longrightarrow \: \sf F= \frac{500}{10} \\ \\ \longrightarrow \: \sf F = 50 \: N$

Now , we have to find acceleration of the body

$\longrightarrow \: \bf Force = Mass \times Acceleration \\ \\\longrightarrow \: \sf 50= 2 \times a \\ \\\longrightarrow \: \sf a = \frac{50}{2}\\ \\\longrightarrow \: \sf a = 25 \: {ms}^{ - 2}$

Now by using 3rd law of motion we will find velocity of the body

$\longrightarrow \: \bf {v}^{2} - {u}^{2} = 2as \\ \\ \longrightarrow \: \sf {v}^{2} - {0}^{2} = 2 \times 25 \times 10 \\ \\ \longrightarrow \: \sf {v}^{2} = 500 \\ \\ \longrightarrow \: \sf v = \sqrt{500} \\ \\\longrightarrow \: \sf v = 100\sqrt{5} {ms}^{ - 1}$

Answer 2

__________________________

★ Gɪᴠᴇɴ :-

• Mass of body = 2kg
• Work done = 500 J
• Distance = 10 m

__________________________

★ Tᴏ Fɪɴᴅ :-

• Speed of body = ?

__________________________

★ Sᴏʟᴜᴛɪᴏɴ :-

To find , speed of the body firstly we need to find force acting on the body & acceleration acted .

As we know that ,

W = F × S

Where,

• W → work = 500J
• F → force = ?
• S → distance = 10m

Substituting the values we have,

➠ 500 = F × 10

➠ 500 ÷ 10 = F

➠ Force = 50 NF = m × a

➠ 50 = 2 × a

➠ 50/2 = a

➠ acceleration = 25 m/s²

________________________

Now , finding speed of the body Using ,

v² = u² + 2( aₙₑₜ )S

Where,

• v → final velocity = ?
• u → initial velocity = 0 m/s
• aₙₑₜ → net acceleration = 25 m/s²
• S → distance = 10m

Note :- Here , the initial velocity ( u ) will be 0 m/s , because the body is starting from rest.

➥ v² = 0² + 2(25)(10)

➥ v² = 500

➥ v = √500

➥ v = 10√5 m/s

Hence , speed of the body is 10√2 m/s

__________________________