Question

a person of mass 40 kg is running with velocity 2m s changes to 6m/s in time interval 60 s . find work done by him during this
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Answer 1

$\bigstar$ Given

A person of mass 40 kg is running with velocity 2 m/s changes to 6 m/s in time interval 60 s

$\bigstar$ To Find

Work done

$\bigstar$ Solution

We know that

$\sf \longrightarrow W= \Delta KE$

Therefore

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

Here

• W = work done
• m = mass
• u = initial velocity
• v = finial velocity

Units

• W = Joule (J)
• m = kilogram (kg)
• u = metre per second (m/s)
• v = metre per second (m/s)

According to the question

We are asked to find work done

Therefore

We must find "W"

Given that

A person of mass 40 kg is running with velocity 2 m/s changes to 6 m/s in time interval 60 s

Hence

• m = 40 kg
• u = 2 m/s
• v = 6 m/s

Substituting the values

We get

$\sf \longrightarrow W=\dfrac{1}{2} \times 40 \times (6^{2}-2^{2}) \ J$

$\sf \longrightarrow W=\dfrac{1}{2} \times 40 \times (36-4) \ J$

$\sf \longrightarrow W=\dfrac{1}{2} \times 40 \times 32 \ J$

$\sf \longrightarrow W=\dfrac{1}{2} \times 1280 \ J$

$\sf \longrightarrow W=\dfrac{1280}{2} \ J$

Therefore

$\sf \longrightarrow W=640 \ J$

Hence

$\checkmark$ Work done = 640 J

Answer 2

Answer:

★ Question ★

a person of mass 40 kg is running with velocity 2m s changes to 6m/s in time interval 60 s . find work done by him during this

★ Given★

• Mass of person = 40 kg
• Velocity of body = 2m/s
• Time changes = 6m/s
• Time interval = 60 second

★ Answer★

$W = \frac {1}{2} × m × (v² - u²)$

$Putting value$

$\: w = \frac{1}{2} \times 40 \: ( {6}^{2} - {2}^{2} )$

$w \: = \frac{1}{2} \times 40 \times (36-4)$

$w \: = \frac{1}{2} \times 40 \times 32$

$\frac{1}{2} \times 1280$

$w \: = \frac{1280}{2} = 640$

Therefore , work done = 640 Joules