Question

Hobbes, the stuffed tiger, has a mass of 28.4 kg. Calvin, the little boy, has a mass of 17.7 kg. In a game of football, Hobbes runs to the right (towards Calvin) at 9.2 m/s. Calvin runs to the left (towards Hobbes) at 12.0 m/s. The two collide and stick together.



What is their final velocity? (Assume that velocities to the right are positive.)

Answer 1

As per the given question,

mass of the Hobbes $(m)=28.4 kg$

mass of the little boy kelvin$(m_1)=17.7 kg$

Speed of the Hobbes (u)=9.2 m/sec

Speed of the kelvin $( u_1)=12 m/sec$

They are running opposite to each other and after the collision, they are getting stick, let the final speed becomes V,

Now, applying the conservation of momentum,

$\Rightarrow mu+m_1u_1=(m+m_1)V$

Now, substituting the values, in the above,

$\Rightarrow V=\dfrac{28.4\times9.2-17.7\times 12}{28.4+17.7}$ m/sec

$\Rightarrow V=\dfrac{48.88}{46.1}m/sec$

$V=1.06m/sec$