Question

A particle of mass 2kg has a momentum of 50 kg m/s. What will be its kinetic energy? ​

Answer 1

Given :

Mass of the particle, m = 2kg

Momentum, p = 50kg

To find :

The kinetic energy of the the particle.

Solution :

first we have to find velocity,

we know,

Momentum is defined as the product of mass multiplied by its velocity .i.e.,

• p = mv

here,

p denotes momentum

m denotes mass

v denotes velocity

by substituting all the given values in the formula,

➠ p = mv

➠ 50 = (2)(v)

➠ v = 50/2

➠ v = 25m/s

Kinetic energy is directly proportional to the mass of the object and to the square of its velocity. It is scalar quantity .i.e.,

➠ K.E = 1/2 mv²

➠ K.E = 1/2 (2)(25)²

➠ K.E = (25)²

➠ K.E = 625 J ${.}$

thus,kinetic energy of the particle is 625J

Remember !

SI unit of energy is Joules (J)

Answer 2

${\huge{\underline{\underline{\rm{Question}}}}}$

★ A particle of mass 2kg has a momentum of 50 kg m/s . What will be its Kinetic Energy ?

${\huge{\underline{\underline{\rm{Answer\checkmark}}}}}$

★ Given :

• Mass (m) = 2 kg
• Momentum (p) = 50 kg m/s

★ To Find :

• Kinetic Energy (K.E.) = ?

★ Solution :

As we know ,

$\boxed{ \sf \: kinetic \: energy \: = \dfrac{1}{2} m {v}^{2} }$

So ,

we have to find velocity (v) .

→ Using the Formula of Momentum (p)

$\boxed{ \sf p = mv}$

$\mapsto \sf \: \cancel{50 }\: \cancel{kg} \: \frac{m}{s} = \cancel2 \cancel{kg}\times v$

$\mapsto \boxed{\sf \: v = 25m {s}^{ - 1} }$

→ Now , put the value of velocity in the Formula of Kinetic Energy

$\star \: \: \sf kinetic \: energy \: = \frac{1}{2} \times m \times {v}^{2}$

$\implies \sf \: k.e. = \frac{1}{ \cancel2} \times \cancel2kg \times {(25m {s}^{ - 1} )}^{2}$

$\implies \boxed{ \sf \: k.e. = 625kg {m}^{2} {s}^{ - 2} }$

As ,

$\underline{ \sf \: 1kg {m}^{2} {s}^{ - 2} = 1joule}$

So,

$\pink \bigstar\boxed{ \rm \: kinetic \: energy \: = 625 \: joules}$