Question

if a body of 5 kg is moving with

72 KM/ Hr speed.

calculate the kinetic Energey​

Answer 1

Given

• Mass = 5 kg
• Speed = 72 km/hr

To Find

• Kinetic Energy

Solution

We know that

$\sf \longrightarrow KE=\dfrac{1}{2}mv^{2}$

Here

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

Units

• KE = Joule (J)
• m = kilogram (kg)
• v = metres per second (m/s)

According to the question

We are asked to find kinetic energy

Therefore

We must find "KE"

Given that

• Mass = 5 kg
• Speed = 72 km/hr

Hence

• m = 5 kg
• v = 72 km/hr = 20 m/s

Substituting the values

We get

$\sf \longrightarrow KE=\dfrac{1}{2} \times 5 \times 20^{2} \ J$

$\sf \longrightarrow KE=\dfrac{1}{2} \times 5 \times 20 \times 20 \ J$

$\sf \longrightarrow KE=\dfrac{1}{2} \times 5 \times 400 \ J$

$\sf \longrightarrow KE=\dfrac{1}{2} \times 2000 \ J$

Therefore

$\sf \longrightarrow KE=1000 \ J$

Hence

Kinetic Energy = 1000 J

Answer 2

Answer:

Given :-

• A body of 5 kg is moving with 72 km/hr.

To Find :-

• What is the kinetic energy.

Formula Used :-

To find kinetic energy, we have to use the formula of kinetic energy,

$\boxed{\bold{\large{K.E\: =\: \dfrac{1}{2}m{v}^{2}}}}$

where,

• K.E = Kinetic Energy
• m = Mass
• v = Velocity

Solution :-

Given :

• Mass (m) = 5 kg
• velocity (v) = 72 km/hr = 72 × $\dfrac{5}{18}$ = 4 × 5 = 20 m/s

According to the question by using the formula we get,

➨ K.E = $\dfrac{1}{2}$ × 5 × (20)²

➨ K.E = $\dfrac{1}{2}$ × 5 × 400

➨ K.E = $\dfrac{1}{\cancel{2}} × {\cancel{2000}}$

➠ K.E = 1000 J

$\therefore$ The kinetic energy of a body is 1000 J .

❖ Extra Information ❖

✦ Kinetic Energy :-

• Kinetic energy is energy possessed by an object in motion.
• Kinetic energy is directly proportional to the mass of an object.

↪ Kinetic energy is measured in units of Joule.

↪ 1 J = 1 kg m²/s²