Two bodies with kinetic energies in the r atio 4 : 1 are moving with e...
Understanding Kinetic Energy and Momentum
To solve the problem, we start by defining the kinetic energy (KE) and momentum (p) formulas:
- Kinetic Energy (KE): KE = 1/2 mv²
- Momentum (p): p = mv
Given that two bodies have kinetic energies in the ratio of 4:1 and move with equal linear momentum, we can denote:
- Mass of body 1: m1
- Mass of body 2: m2
- Velocity of body 1: v1
- Velocity of body 2: v2
Setting Up the Ratio of Kinetic Energies
Since the kinetic energies are in the ratio 4:1, we can write:
- KE1 / KE2 = 4 / 1
This leads us to:
- (1/2)m1v1² / (1/2)m2v2² = 4 / 1
Which simplifies to:
- (m1v1²) / (m2v2²) = 4 / 1
Using Equal Momentum
Given that both bodies have equal momentum, we have:
- m1v1 = m2v2
From this, we can express v2 in terms of v1:
- v2 = (m1/m2)v1
Substituting for Velocity
Now, substitute v2 into the kinetic energy ratio:
- m1v1² / m2((m1/m2)v1)² = 4 / 1
This simplifies to:
- m1v1² / (m2(m1²/m2²)v1²) = 4 / 1
Which further simplifies to:
- m2/m1 = 4 / 1
Conclusion: Mass Ratio
Rearranging gives us:
- m1/m2 = 1/4
Thus, the ratio of their masses is 1:4, confirming that the correct answer is option 'D'.