A rock is thrown horizontally with a speed of 20 m/s from the edge of a high cliff. It lands 80 m from the cliff's base. How tall is the cliff?

(II) At serve, a tennis player aims to hit the ball horizontally. What minimum speed is required for the ball to clear the 0.90-m-high net about 15.0 m from the server if the ball is 'launched' from a height of 2.30 m? Where will the ball land if it just clears the net (and will it be 'good' in the sense that it lands within 7.0 m of the net)? How long will it be in the air? See Fig. 3–50.

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If a baseball pitch leaves the pitcher's hand horizontally at a velocity of 130 km/h, by what % will the pull of gravity change the magnitude of the velocity when the ball reaches the batter, 18 m away? For this estimate, ignore air resistance and spin on the ball.

A hunter aims directly at a target (on the same level) 38.0 m away. 

(a) If the arrow leaves the bow at a speed of 21.3 m/s, by how much will it miss the target? 

Which of the following quantities are constant during projectile motion?