A falling stone is at a certain instant 90 feet above the ground. Two seconds later it is only 10 feet above the ground. If it was thrown upward with an initial speed of 3 feet per second, from what height was it thrown?
a) 5623⁄64 feet
b) 5943⁄64 feet
c) 6007⁄64 feet
d) 5815⁄64 feet
e) 5879⁄64 feet

Question

anonymous · Answer

Please help me :(

rsadhvika · Answer

you sure the options are correct ?

anonymous · Answer

Yeah, I don't know if you can see the division sign. But all the numbers are divided by 64

rsadhvika · Answer

omg ! yeah just noticed the division symbol

rsadhvika · Answer

u're given value of 'g' to use ?

rsadhvika · Answer

g=9.81

or

g = 10

which one to use ?

anonymous · Answer

9.8 please

rsadhvika · Answer

wolfram gives this :- http://www.wolframalpha.com/input/?i=9%2F19.6%2Bh-9.8%2F2t%5E2%3D90%2C+9%2F19.6%2Bh-9.8%2F2%28t%2B2%29%5E2%3D10

atlas · Answer

use s=ut +0.5at^2

anonymous · Answer

oh my. wolfram doen't match any of my options

anonymous · Answer

Thanks atlas

anonymous · Answer

but what is my a?

atlas · Answer

you have to of course take it in ft/s^2

atlas · Answer

i guess g = 32ft/s^2 but i am not sure...........check it

atlas · Answer

yeah I am right

rsadhvika · Answer

ahh m->ft converstion for g

anonymous · Answer

oh. okay.