Question

Abody of mass 10 kg starts from rest, and accelerates uniformly with a velocity of 25 m/s after having covered a distance of 20 m. Find the amount of work done on the body.

Answer 1

Given

• Mass = 10 kg
• Initial Velocity = 0 m/s
• Final Velocity = 25 m/s
• Distance = 20 cm

To Find

• Work done on the body

Solution

● Here we shall first find the acceleration of the body using the third equation of motion, then use Newton's second law to Find the force and then work is equal to the product of the Force and the distance

✭ As per the Question :

→ v²-u² = 2as

→ 25²-0² = 2 × a × 20

→ 625 = 40a

→ 625/40 = a

→ Acceleration = 15.625

━━━━━━━━━━━━━━━

• Then we shall find the Force Applied

→ F = ma

→ F = 10 × 15.625

→ F = 156.25 N

✭ Work Done

→ Work = F × s

→ Work = 156.25 × 20

→ Work = 3125 J

∴ The work done in changing the velocity of the body here is 3125 J

Answer 2

Answer:

Given :-

• Mass of body (M) = 10 Kg
• Initial velocity (U) = 0 m/s (as it is starting from rest)
• Final velocity (V) = 25 m/s
• Distance travelled (S) = 20 m

To Find :-

Amount of work done

SoluTion :-

Firstly we shall find its acceleration

✮ V² - U² = 2as

Here,

V = Final Velocity

U = Initial velocity

A = Acceleration

S = Distance

➞ 25² - 0² = 2(a)(20)

➞ 625 - 0 = 40(a)

➞ 625 = 40a

➞ A = 625/40

$\sf \huge \bf \: Acceleration = 5.625$

Now,

Finding work done

✮ W = F × S

➞ Work done = 15.625 × 20

➞ Work done = 3125 Joule