Question

Kyle, a 95.0 kg football player, leaps straight up into the air (with no horizontal velocity) to catch a pass. He catches the 0.430 kg ball precisely at the peak of his jump, when he is 0.589 meters off the ground. He hits the ground 0.0409 meters away from where he leapt. If the ball was moving horizontally when it was caught, how fast was the ball traveling?

Answer 1

Answer:

The initial speed of the ball was 26.2 m/s

Explanation:

When the football player is in the air at his maximum height the vertical component of velocity is zero, To obtain the horizontal velocity when the player catches the ball we need to apply the linear momentum conservation theorem:

$m_1*v_{o1}+m_2*v_{o2}=m_t*v_f\\0.430kg*(v)+m_2*(0)=mt*vt$

we need to obtain the time taken to go down.

$y=Y_o+v_o*t-\frac{1}{2}g*t^2\\\\0=0.589-4.9t^2\\solving:\\t_1=0.346s$

We have a horizontal displacement and the time taken to stop, so:

$v_f=\frac{d}{t}=\frac{0.0409m}{0.346s}=0.118m/s$

so:

$0.430kg*(v)+m_2*(0)=(m1+m2)*vt\\v=\frac{(95.0kg+0.430kg)*0.118m/s}{0.430kg}\\\\v=26.2m/s$