A goalkeeper kicks a 0.4 kg soccer ball with a force of 945.9 N to a team mate 8

Question

A goalkeeper kicks a 0.4 kg soccer ball with a force of 945.9 N to a team mate 81.9 m away. The ball is initially at rest on the ground and the kicker’s foot is in contact with the ball for 0.01 s. The ball is kicked at a 59.1degree angle to the horizontal. Neglect air resistance and rotational motion of the ball. a) The momentum change of the soccer ball in when kicked is _____kgm/s b) The speed of the kicked soccer ball is ____ m/s. c) The ball rise to a height of ____ m. d) The ball is in the air for _____ s. e) The total mechanical energy of the soccer ball in flight is ____ J.

Explanation / Answer

m= 0.4kg

F= 945.9N

R = 81.9

=59.1 deg

a) momentum change = m(v2-v1) = F*t = 945.9*0.01 = 9.459kg.m.s

b)v1=0, v2= ?

m*(v2-v1) = 9.459 => 0.4*v2 = 9.459 => v2= 9.459/0.4 =23.6475m/s

c) rise of height = Hmax = (v2*sin( ))^2/(2*g) = (23.6475*sin(59.1))^2/(2*9.81) =20.98

d) time of flight = 2*v2*sin()/g = 2*23.6475*0.8580/9.81 =4.1365sec

e) Total mechanical energy of soccer = kinetic energy at ground = 1/2*0.4*23.6475^2 =111.80

= P.E+K.E at max height ==0.4*9.81*20.98+0.5*0.4*(12.14)^2 =111.80

b)

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