A soccer player with a mass of 60 kg is traveling at 8 m/s when he completes a corner kick on a 0.45 kg soccer ball. The soccer ball travels toward the goal at a speed of 35 m/s. In this elastic collision, what is the speed of the soccer player immediately after kicking the ball?

A5.4 m/s
B7 m/s
C7.7 m/s
D8 m/s

It must be noted that during an elastic collision both the momentum and kinetic energy are conserved. For the kinetic energy, it can be solved through the equation,
KE = 0.5mv²
Equating the kinetic energies before and after collision,
0.5(60)(8 m/s)² = (0.5)(60)(x²) + (0.5)(0.45)(35 m/s)²
The value of x from the equation is approximately 7.40 m/s

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Muscardinus Muscardinus · Answer 2 · 2019-10-22T05:35:42-04:00

Answer:

v = 7.73 m/s

Explanation:

It is given that,

Mass of the player, m₁ = 60 kg

Initial speed of the player, u₁ = 8 m/s

Mass of the soccer ball, m₂ = 0.45 kg

Initial speed of the player, u₂ = 0 (at rest)

After the collision,

Final speed of the player, v₁

Final speed of the ball, v₂ = 35 m/s

Using the conservation of linear momentum to find the final speed of the player. Mathematically, it is given by :

\(m_1u_1+m_2u_2=m_1v_1+m_2v_2\)

\(m_1u_1=m_1v_1+m_2v_2\)

\(60\times 8=60\times v_1+0.45\times 35\)

\(v_1=7.73\ m/s\)

So, the speed of the soccer player immediately after kicking the ball is 7.73 m/s. Hence, this is the required solution.