# Need help calculating maximum height

1. Jun 6, 2009

### farhan769

1. The problem statement, all variables and given/known data
A doctor, preparing to give a patient an injection, squirts a small amount of liquid straight upward from a syringe.
a) If the liquid emerges with a speed of 1.3 , how long does it take for it to return to the level of the syringe?
b) What is the maximum height of the liquid above the syringe?

2. Relevant equations
y=(vi)(t)-.5(g)(t^2)
d=vt
i'm really not sure what equation to use

3. The attempt at a solution
for part a i use y=(vi)(t)-.5(g)(t^2)
0=1.3t-.5(-9.8)(t^2)
t=.27s

I'm really not sure about part b, could someone help me with it
thanks

2. Jun 6, 2009

### LowlyPion

OK. We'll go with 1.3 m/s (you must include units ... it matters).

The easy way is to observe that

v = a*t

so the time to max height will be given by

1.3 = 9.8*t or t = 1.3/9.8.

Since total time is time up + time down ... double that giving 1.3*2/9.8

Since y = 1/2*g*t2 then just use the time found to max height from before of 1.3/9.8