Question

Question:-

A body of mass 60 kg is moving with a velocity of 50 m s⁻¹. What would be the change in its kinetic energy if the velocity is halved?
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Thank you!
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Answer 1

Answer:-

Given:-

Mass of a body (m) = 60 kg

Velocity of the body (v) = 50 m/s

We know that,

Kinetic Energy (K.E) = 1/2 mv²

So,

⟹ K.E = 1/2 * 60 * (50)²

⟹ K.E = 30* 2500

⟹ K.E = 75000 J

Now,

We have to find the decrease in kinetic energy of the body if the velocity is halved.

• New velocity = 50/2 m/s = 25 m/s.

Therefore,

⟹ K.E' = 1/2*(60)*(25)²

⟹ K.E' = 30*625

⟹ K.E' = 18750 J

Now,

Change in the Kinetic energy = K.E - K.E' (K.E > K.E')

⟹ ∆K.E = (75000 - 18750) J

⟹ ∆K.E = 56250 J

∴ The kinetic energy of the body decreases by 56250 J if the velocity is halved.

Answer 2

Here Is Your Answer!

Given :

• Mass of the body = 60kg
• 1st Velocity = 50m/s
• 2nd Velocity = 25m/s (half of 50)

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To Find :

The change in the kinetic energy of the body if the Velocity is halved

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Formula To Be Applied :

We will use the formula of kinetic energy :

• KE = ½ × mass × velocity²

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Solution :

Given, Mass = 60 kg

1st Velocity = 50m/s

So, the Kinetic energy

$\displaystyle \rm \implies ke = \frac{1}{2} \times mass \times {velocity}^{2}$

$\displaystyle \rm \implies ke = \frac{1}{2} \times 60 \times {50}^{2}$

$\implies \displaystyle \rm ke = 30 \times 2500$

$\red{ \underline{ \boxed{\displaystyle \rm \implies ke = 7.5 \times {10}^{4} }}}$

So, Kinetic Energy = 7.5 × 10⁴ Joules

Let, this KE be (A)

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Given, Mass = 60,000 g

Velocity = 25m/s

So, Kinetic Energy:

$\displaystyle \rm \implies ke = \frac{1}{2} \times 60 \times {25}^{2}$

$\implies \displaystyle \rm ke = 30 \times 625$

$\red{ \underline{ \boxed{ \implies \displaystyle \rm ke = 1.875 \times {10}^{4} }}}$

So, Kinetic Energy = 1.875×10⁴Joules

Let, this KE be (B)

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Comparison :

1] Ratio Of Kinetic Energy :

Ratio of Kinetic energy of A to B :

A : B

= 7.5×10⁴ : 1.875×10⁴

= 7.5 : 1.875

= 4 : 1

So, We get that A = 4B

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2] Difference Comparison:

A = 75,000 J

B = 18,750,J

So, A-B

= 75,000 - 18,750

= 56,250 J

So, Difference Of A and B = 56,250 J

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