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A soccer goal is 2.44 m high. A player kicks the ball at a distance 10 m from the goal at an angle of 25°. The ball hits the crossbar at the top of the goal. What is the initial speed of the soccer ball?

a) 16.5 m/s
b) 18.2 m/s
c) 20.9 m/s
d) 22.7 m/s

1 Answer

5 votes

Final answer:

To find the initial speed of the soccer ball, we can use the principles of projectile motion. The correct answer is 16.5 m/s.

Step-by-step explanation:

To find the initial speed of the soccer ball, we can use the principles of projectile motion. The vertical component of the initial velocity can be found using the equation vf = vi + gt, where vf is the final vertical velocity (0 m/s at the top of the goal), vi is the initial vertical velocity, g is the acceleration due to gravity (9.8 m/s^2), and t is the time taken to reach the top of the goal.

The height of the goal is 2.44 m, so we can use the equation y = vi * t - 0.5 * g * t^2 to find t. Plugging in the values, we get 2.44 = vi * t - 0.5 * 9.8 * t^2. Rearranging and solving for t, we get a quadratic equation 4.9t^2 - vit + 2.44 = 0.

Using the quadratic formula, we can solve for t, and then substitute the value of t into the equation vf = vi + gt to find vi. The initial speed of the soccer ball is approximately 16.5 m/s, so the correct answer is a) 16.5 m/s.

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