Question

A stone of mass 200 gram has a kinetic energy of 100 joules Calculate the speed of the moving stone .​

Answer 1

Question :-

A stone of mass 200 grams has a kinetic energy of 100 joules . Calculate the speed of the moving stone ?

ANSWER

Given :-

A stone of mass 200 grams has a kinetic energy of 100 joules.

Required to find :-

• Speed of the moving stone ?

Solution :-

We are given that !

A stone of mass 200 grams has a kinetic energy of 100 joules

So,

Q) What is Kinetic energy ?

A) The energy possessed by a moving body is Kinetic energy.

Formula for kinetic energy is;

K.E. = (1)/(2) mv²

Here,

m = mass of the body

v = velocity of the body

Units of K.E. are Joules , Mass is kg & velocity is m/s

So,

Let's use this concept in the above question :-)

We have;

Mass of the stone = 200 grams {convert to kg}

= (200)/(1000)

= 0.2 kg

K.E. possessed by the stone = 100 joules

Now,

Using the formula !

K. E. = (1)/(2) mv²

v = √[(K. E. x 2)/(m)]

v = √[(100 x 2)/(0.2)]

v = √[(100 x 2 x 10)/(2)]

v = √[(100 x 10)]

v = 10√10 m/s

v = 10 x 3.16 (since, √10 = 3.16.. )

v = 31.6 m/s

Therefore,

speed of the moving stone = 31.6 m/s

Answer 2

Given

• Mass of stone (m) = 200 g
• Kinetic energy (K.E) = 100 J

To find

• Speed (v)

Solution

Kinetic energy = 1/2 mv²

• m - mass
• v - velocity/speed

We have,

• mass = 200 g
• mass = 200/1000

Since energy is in S.I unit.

• mass = 0.2 Kg
• K.E = 200 g

Substituting in the formula, we get :-

• K.E = 1/2 mv²
• 200 = 1/2 × 0.2 × v²
• v² = 100 × 2/0.2
• v = √100 × 10 (√ on both sides)
• v = 10√10
• v = 10 × 3.16
• v = 31.6

Hence, the speed or velocity of the stone is 31.6 m/s