Question

A particle falling under gravity describes 80 ft in a certain second.How long does it take to describe the next 112 ft?

Answer 1

Let us consider the velocity of particle when it completes 80 ft is v 
and this velocity will be initial velocity for the 112 ft height. let us
consider it takes t time.
g = 32 ft/s^2
v^2 = u^2 + 2gh
v^2 = 0^2+ 2* 32* 80
v = √(64*80)
v = 8x4√(5)
v = 71.55 ft/s

now h = vt+0.5 x g x t^2
112 = 71.55t+0.5 x 32 x t^2
On solving 
t = -b ±√(b^2-4ac) / 2a

t = 1.2 sec

i hope it will help you

regards

Answer 2

Explanation:

ANSWER

Let us consider the velocity of particle when it completes 80 ft is V and this velocity will be initial velocity for 112 ft height. Let us consider it takes t time.

g=32ft/s

2

V

2

=u

2

+2gh

V

2

=O

2

+2×32×80

V=

64×80

V=8×4

5

V=71.55 ft/s

now, h=vt+0.5×g×t

2

112=71.55t+0.5×32×t

2

On solving,

t=−h±

h

2

−4ac

/2α

t=1 seconds