Help Physics (I think its free fall)

AI Thread Summary
The discussion revolves around calculating the time it takes for liquid squirted upward from a syringe to return to its original level and determining its maximum height. The initial calculations suggested a return time of 0.30 seconds and a maximum height of approximately 0.11 meters. However, a correction was noted regarding the use of the initial velocity and the conditions at the peak of the trajectory. The correct approach involves recognizing that the initial velocity is not zero at the peak. Overall, the calculations were mostly accurate, with minor adjustments needed for precision.
coriimon
Messages
2
Reaction score
0
A doctor, preparing to give a patient an injection, squirts a small amount of liquid straight upward from a syringe. If the liquid emerges with a speed of 1.5 m/s
how long does it take for it to return to the level of the syringe?
what is the maximum height of the liquid above the syringe?

The Attempt at a Solution



I got .30seconds to return to the level of the syringe
and the max height at around .11 meters


am I right?? just want to make sure
 
Physics news on Phys.org
If you show what equations you used and how you got those answers, it's easier to check your work.
 
A doctor, preparing to give a patient an injection, squirts a small amount of liquid straight upward from a syringe. If the liquid emerges with a speed of 1.5 m/s
how long does it take for it to return to the level of the syringe?
what is the maximum height of the liquid above the syringe?

whoops sorry

I found the time it takes to return to the level of the syringe by using this equation

v=v(initial)=at
1.5m/s=0m/s+(9.81m/s^2)(t)
t=.15 seconds
to account for the time to return to the syringe I multiplied t by 2 so t=.30 seconds

to find the maximum height I used the equation
v^2=V(initial^2 +2a(x-x(initial))
2.25=19.62x
.11 m
 
coriimon said:
v=v(initial)=at
1.5m/s=0m/s+(9.81m/s^2)(t)
t=.15 seconds
to account for the time to return to the syringe I multiplied t by 2 so t=.30 seconds

I agree with both your final answers, but if I were grading this I might knock off a point here.

If you're finding the time it takes to reach the top of the trajectory, v is not 1.5 m/s there, as you've indicated. Also, the initial velocity isn't 0.

If you're finding the time it takes to drop from top of the trajectory, then the equation is okay ... provided you meant to use down as the + direction.

But it would only be a minor deduction. You pretty much got it on the nose.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top