Question

WILL FAN AND MEDAL!
Word problems are my weakness..
7. If an object is dropped from a height of 200 feet, the function h(t)=-16t^2+200 gives the height of the objects after t seconds. Approximately, when will the object hit the ground?
A.200.00 seconds
B.184.00 seconds
C.3.54 seconds
D.0.78 seconds

Answer 1

8. A ball is thrown in the air with an upward velocity of 28ft/s. Its height (h) in feet after t seconds is given by the function h=-16t^2+28t+7. How long does it take the ball to reach its maximum height? What is the ball's maximum height? Round to the nearest hundreth, if necessary.
A. Reaches a maximum height if 7 feet after 1.75 seconds
B. Reaches a maximum height of 43.75 feet after 0.88 seconds
C. Reaches a maximum height of 17.5 feet after 0.88 seconds
D. Reaches a maximum height of 19.25 feet after 0.88 seconds

Answer 2

Make h = 0 and solve for t

Answer 3

13. A catapult launches a boulder with an up ward velocity of 184 feet per second. The height of the boulder,(h), in feet after t seconds is given by the function h(t)=-16t^2+184t+20. How long does it take the boulder to reach its maximum height? Round to the nearest hundredth, if necessary.
A. Reaches a maximum height of 11.6 feet after 5.75 seconds
B. Reaches a maximum height of 549 feet after 11.5 seconds
C. Reaches a maximum height of 549 feet after 5.75 seconds
D. Reaches a maximum height of 23.2 feet after 11.6 seconds

Answer 4

@alekos can u take me through it step by step because like i said word problems are my weakness and i don't understand

Answer 5

0 = -16t^2 + 200

Now solve for t

Answer 6

C?

Answer 7

@alekos is it C?

Answer 8

@iGreen

Answer 9

@jakashaka123 do you know?
@iGreen do you know?

Answer 10

im sorry i dont =(

Answer 11

@Michele_Laino @dan815

Answer 12

@jakashaka123 thats okay!

Answer 13

question 7)
If I call with \tau the time when ball hits the ground, then we have to request that the subsequent condition holds:
\[\Large h\left( \tau \right) = 0\]
or:
\[ \Large - 16{\tau ^2} + 200 = 0\]
so what is \tau?

Answer 14

@Michele_Laino i thought 7 is C

Answer 15

okay so i did 7.C 8.D and 13 i need help with

Answer 16

@iGreen @dan815

Answer 17

#1=3.54sec because 16t^2=200

Answer 18

yeah @jamaica25 i got that one but i need help with the third one

Answer 19

#2 19.26 ft after 0.88sec
because time =-b/2a =-28/2*16=0.88
sub in equation h=19.26

Answer 20

@jamaica25 i got that one too i need the third one

Answer 21

if you follow my answer the third is the same reasoning

Answer 22

can u like walk me through the problem so i understand it better? @jamaica25

Answer 23

use the formula -b/2a =-184/(2*16) =5.74 sec.

Answer 24

so the third one is either a or c? @jamaica25

Answer 25

yes can you use the formula?

Answer 26

yes? @jamaica25

Answer 27

put 5.74 into the height formula to get which height

Answer 28

a? @jamaica25

Answer 29

no

Answer 30

:( c? @jamaica25

Answer 31

-16(5.75)^2+184(5.74)+20 =549

Answer 32

ooh i see now

Answer 33

the answers are not important understanding the formula is

Answer 34

yeah i was really trying to understand the formula for this problem but these types of problems are my weakness in math

Answer 35

ok

Answer 36

Thank you so much for all your help!

Answer 37

@jamaica25 i have one more like this do you think you can help?