Unit 9 Lesson 6 Answer Key
1. Kirby hits a ball when its 4 ft above the ground with an initial velocity of 120 ft/sec.
The ball leaves the bat at a 30 degree angle with the horizontal.
(a) How long is the ball in the air?
3.81 seconds (The time at the x-intercept)
(b) Determine the horizontal distance that the ball traveled.
397 feet (the x-intercept)
(c) What is the max height the ball reaches? At what time does the ball reach its max
height?
60.2 feet at 1.91 seconds.
(d) Does the ball clear a 30 foot fence that is 350 feet from home plate?
The ball does not clear the fence. When the ball is 350 feet away at 3.368
seconds it is at a height of 24.6 feet.
2. James hits golf balls of a practice tee with an initial velocity of 160 ft/sec. How far
down the fairway does the ball hit the ground if it comes off the club making an
angle of 15 degrees with the horizontal?
The ball is hit 400 feet down the fairway (the x-intercept).
3. Delmar attempts a 43 yard field goal. He kicks the ball at a 41 degree angle with an
initial velocity of 70 feet per second. The goal post is 15 feet high. Is the kick long enough to
make the field goal?
At 0.815 seconds the ball is kicked 43 yards and is at a height of 26.8 yards. 26.8
yards equals 80.4 feet so Delmar will make the field goal.
4. Kaylee is practicing free throws for an upcoming basketball game. She releases the ball
with an initial velocity of 24 ft/sec at an angle of 53 degrees. The horizontal distance from
the free throw line to the front of the rim is 13 feet. The vertical distance from the floor to
the rim is 10 feet. The front of the rim is 2 feet from the backboard. She releases the shot
4.75 feet from the ground. Does Kaylee make the basket?
After the ball travels a horizontal distance of 11 to 13 feet (because the rim is 2 feet from
the backboard) the height of the ball will change from 10.06 feet to 9.04 feet. Since the
height of the ball is slightly above 10 feet at edge of the rim, Kaylee will make the basket.