Question

A moving body of mass 30kg has 60J of K.E. Calculate its speed

(a)2m/sec

(b)3m/sec

(c)4m/sec

(d)5m/sec

​

Answer 1

Given :-

Mass of the moving body = 30 kg

Kinetic energy of the moving body = 60 J

To Find :-

The speed of the moving body.

Analysis :-

Here we are given with the mass and kinetic energy of the moving body.

In order to find the speed of the moving body substitute the values such that kinetic energy is equal to kinetic energy is equal to mass multiplied by velocity square divided by two.

Solution :-

We know that,

• KE = Kinetic energy
• m = Mass
• v = Velocity

Using the formula,

$\underline{\boxed{\sf Kinetic \ energy= \dfrac{1}{2} mv^2}}$

Given that,

Kinetic energy (KE) = 60 J

Mass (m) = 30 kg

Substituting their values,

⇒ 60 = 1/2 × 30 × v²

⇒ 30 × v² = 2 × 60

⇒ 30 × v² = 120

⇒ v² = 120/30

⇒ v² = 4

⇒ v = √4

⇒ v = 2 m/s

Therefore, the speed of the moving body is 2 m/s.

Answer 2

Answer:

Given :-

Mass of the moving body = 30 kg

Kinetic energy of the moving body = 60 J

To Find :-

The speed of the moving body.

Analysis :-

Here we are given with the mass and kinetic energy of the moving body.

In order to find the speed of the moving body substitute the values such that kinetic energy is equal to kinetic energy is equal to mass multiplied by velocity square divided by two.

Solution :-

We know that,

KE = Kinetic energy

m = Mass

v = Velocity

Using the formula,

Kinetic energy=2/1

mvm²

Given that,

Kinetic energy (KE) = 60 J

Mass (m) = 30 kg

Substituting their values,

⇒ 60 = 1/2 × 30 × v²

⇒ 30 × v² = 2 × 60

⇒ 30 × v² = 120

⇒ v² = 120/30

⇒ v² = 4

⇒ v = √4

⇒ v = 2 m/s

Therefore, the speed of the moving body is 2 m/s.