Question

$\huge\bold{QUESTION:-}$

The kinetic energy of an object moving with a velocity of 5 m/s is 25 J. Find the mass of the object. What will be its kinetic energy when its velocity is made:-

i) 2 times
ii) 3 times


Justify your answers...


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Answer 1

$\huge\bold\red{HOLA!!}$

Given that:

Mass = m, v = 5 m/s and KE = 25 J

KE = mv

2

25 =x (5)

25x 2

(5)

→m = 2 kg

i. When the velocity is made twice:

KE, =

m(2v)

= 4x

or KE, = 4xKE = 4 x 25

or KE, = 100)

ii. When the velocity is made thrice:

KE, = m(3v}

=

9x

mv2

or KE, = 9xKE = 9x25

or KE, = 225 J

Answer 2

Question :--- The kinetic energy of an object moving with a velocity of 5 m/s is 25 J. Find the mass of the object. What will be its kinetic energy when its velocity is made:-

i) 2 times

ii) 3 times

Formula used :---

→ Kinetic energy is directly proportional to the mass of the object and to the square of its velocity: K.E. = 1/2 * m * v².

→ If the mass has units of kilograms and the velocity of meters per second, the kinetic energy has units of kilograms-meters squared per second squared.

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Solution :----

Given,,

→ Kinetic Energy = 25J

→ Velocity = 5m/s.

→ Let Mass = m

Putting all values in above Told formula we get,

→ 25 = 1/2 * m * (5)²

→ 25*2 = 25 * m

Dividing both sides by 25 we get,

→ m = 2 kg..

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Case (1) :---

when velocity is Two times ,

→ New velocity = 5 * 2 = 10m/s.

→ Mass = 2kg.

So,

→ KE = 1/2 * 2 * (10)²

→ KE = 100 J.

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Case (2) :---

when velocity is Three times ,

→ New velocity = 5 * 3 = 15m/s.

→ Mass = 2kg.

So,

→ KE = 1/2 * 2 * (15)²

→ KE = 225 J.

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