Question

On a very muddy football field, a 110kg linebacker tackles an 85kg halfback. Immediately before the collision, the linebacker is slipping with a velocity of 8.5m/s north and the halfback is sliding with a velocity of 7.2m/s east.

i have no idea how to even set up this problem .. a walk through would be appreciated (:

Answer 1

Using conservation of energy and momentum you can solve this question.

M_l = mass of linebacker
M_ h = mass of halfback
V_l = velocity of linebacker
V_h = velocity of halfback

So for conservation of momentum, \[\rho = mv\]

\[M_l \times V_li + M_h \times V_hi = M_l \times V_lf + M_h \times V_hf \]

For conservation of energy (kinetic) \[E_k = 1/2mv^2\]

\[1/2mV_{li}^2 + 1/2mV_{hi}^2 = 1/2mV_{lf}^2 + 1/2mV_{hf}^2\]

Where i and h stand for initial and final values.

We are already told the masses, \[M_l = 110kg\]

\[M_h = 85kg\]

and the final velocities \[V_{fi} = 8.5ms^{-1}\] and \[V_{ih} = 7.2ms^{-1}