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Calculate Parameter x from Momentum Ratio of Accelerated Masses

Two masses of 3.4 kg3.4\text{ kg} and 2.5 kg2.5\text{ kg} are accelerated from an initial speed of 5 m/s5\text{ m/s} and 12 m/s12\text{ m/s}, respectively. The distances traversed by the masses in the 5th5^{\text{th}} second are 104 m104\text{ m} and 129 m129\text{ m}, respectively. The ratio of their momenta after 10 s10\text{ s} is x8\frac{x}{8}. The value of xx is _______.

Official Numerical Answer9

Topics & Concepts

Step-by-Step Solution

To find the accelerations a1a_1 and a2a_2 of the two masses, we use the formula for distance covered in the nthn^{\text{th}} second: Sn=u+a2(2n1)S_n = u + \frac{a}{2}(2n - 1)

For the first mass (m1=3.4 kgm_1 = 3.4\text{ kg}, u1=5 m/su_1 = 5\text{ m/s}): 104=5+a12(251)104 = 5 + \frac{a_1}{2}(2 \cdot 5 - 1) 99=92a1    a1=22 m/s299 = \frac{9}{2} a_1 \implies a_1 = 22\text{ m/s}^2

For the second mass (m2=2.5 kgm_2 = 2.5\text{ kg}, u2=12 m/su_2 = 12\text{ m/s}): 129=12+a22(251)129 = 12 + \frac{a_2}{2}(2 \cdot 5 - 1) 117=92a2    a2=26 m/s2117 = \frac{9}{2} a_2 \implies a_2 = 26\text{ m/s}^2

Next, we calculate their velocities after t=10 st = 10\text{ s} using v=u+atv = u + at: v1=5+22(10)=225 m/sv_1 = 5 + 22(10) = 225\text{ m/s} v2=12+26(10)=272 m/sv_2 = 12 + 26(10) = 272\text{ m/s}

The momenta p1p_1 and p2p_2 after 10 s10\text{ s} are: p1=m1v1=3.4×225=765 kgm/sp_1 = m_1 v_1 = 3.4 \times 225 = 765\text{ kg}\cdot\text{m/s} p2=m2v2=2.5×272=680 kgm/sp_2 = m_2 v_2 = 2.5 \times 272 = 680\text{ kg}\cdot\text{m/s}

Taking the ratio of their momenta: p1p2=765680=98\frac{p_1}{p_2} = \frac{765}{680} = \frac{9}{8}

Given that p1p2=x8\frac{p_1}{p_2} = \frac{x}{8}, we get: x=9x = 9

Calculate Parameter x from Momentum Ratio of Accelerated Masses | Physics PYQ Solution - JEE Challenger