Question

A football player throws a 400 g football at 30 degree to the horizontal. Being in a good physical condition, he is able to imnd Initial kinetic energy of 100 J to the ball. The ball is caught at exactly the same height above the ground as It was thrown. Full points will be awarded for the correct answer to the following question. How far does the ball travel in the horizontal direction? If the full credit cannot be awarded, then partial credit will be awarded for the correct answers to the following questions: What is the initial speed of the ball (immediately after It has separated from the athlete's hand) What is the vertical component of the ball's initial velocity? What is the value of vertical acceleration of the ball? How long will it take for the ball to get to the maximum height? How long will it take for the ball to get up to the maximum and then fall back to the initial height? What is the horizontal component of the ball's initial velocity? What is the value of horizontal acceleration of the ball? How far will the ball travel in the horizontal direction within the time found in v)?

Answer 1

E = 100 J

1/2 mV^2 = 100

V = 22.36 m/s

Vh = horizontal velocity = 19.36 m/s

Vv = vertical velocity = 11.18 m/s

horizontal distance = V^2sin(2*30) / g = 44.18 m

i) initial speed = 22.36 m/s

ii) Vv = vertical velocity = 11.18 m/s

iii) vertical acceleration will be downward due to gravity = g = 9.8 m/s^2

iv) t = Vsin(30) / g = 1.14 sec

v) T = 2t = 2.28 sec

vi) Vh = horizontal velocity = 19.36 m/s

vii) horizontal acceleration = 0