David and Goliath
David and Goliath
David and Goliath
The enemy army had a soldier named Goliath. Goliath was very big,
very strong, and very tall. He was a giant! Every day Goliath would
shout mean things at King Saul and the Israelites. Then he would
say, “Choose someone to come and fight me. If he wins, we will
serve you. If I win, you must serve us.”
King Saul and his men were afraid. They were used to fighting
together. And Goliath was so big that no one wanted to fight Goliath
by himself.
One day, David came to the camp to bring his brothers some food.
David heard the giant yelling. David was very angry because of all
the mean things Goliath was saying about God and the Israelites.
David couldn’t understand why no one would fight Goliath. David
knew that God was stronger than the giant. And David knew God
would help the Israelites win.
One of the soldiers told King Saul what David was saying. So King
Saul sent for David. When David arrived, he told King Saul, “I will
fight Goliath.”
Saul wanted David to wear the king’s armor and use his sword. But
when David tried to walk around with all those things on, he said, “I
can’t fight in these!” And he took them off.
So King Saul said, “Go, and the Lord be with you.” Then David went
and found five smooth rocks to use with his sling. Now he was
ready to fight the giant!
PROBLEM
David aimed his sling at Goliath and let his little weapon - a fist size
rock fly into the air with an upward velocity of 20 ft/sec. The
equation that gives the height (h) of the ball at any time (t) is: h(t)=
-16t2 + 20 (ft/s)t + 5. Due to his size it takes 5 seconds before
Goliath can make a move or take a single step. David having laser
sharp focus attempted to crack the enemy’s forehead. Since he is
so tall, the rock can only hit Goliath in the forehead at its maximum
altitude. Will David be able to take Goliath down in the first attempt?
What is the distance of the rock from the ground when it will strike
Goliath’s forehead?
vertex formula
a = (-16)
b = 20
c=5
It takes 0.625 seconds for the rock to reach its maximum height
Since Goliath can move only after 5 seconds, he can wont be able
to avoid David’s shot. He will be hit at first attempt
B. What is the distance of the rock from the ground when it will
strike Goliath’s forehead?
= -16(0.390625) + 12.5 + 5
= -6.25 + 12.5 + 5
h(t) = 11.25ft