a syringe with a plunger diameter of 2.0cm is attached to a hypodermic needle with a diameter of 1.5mm, What minimum force must be applied to the plunger to inject a fluid to a vein, where the blood pressure is 12torr ?

Question

anonymous · Answer

This is exactly like the problem with the car :)

anonymous · Answer

will i convert torr to pascal?

anonymous · Answer

|dw:1399090769387:dw|
(Not to scale...at all)

But we can treat it similarly.

anonymous · Answer

Yeah, you'll want to convert everything to standard units (m, pascal, etc) just to save some headache.

anonymous · Answer

hahaha..wait I will convert first

anonymous · Answer

101325/760 Pa = 1 torr, so multipied by 12,,we can get,, 1599.868 Pa...

anonymous · Answer

what formula will i use...?

anonymous · Answer

$$Pressure = \frac{Force}{Area}$$

I'm thinking, though.

Since there isn't an actual barrier (like a piston) that the fluid has to push on, If the pressure in the needle is higher than the pressure in the vein, the fluid should move outward. The pressure in the needle equals the pressure in from the plunger.

This would mean that we could use the pressure of the blood for pressure, the cross-sectional area of the plunger for area, solve for force, and we'd be done.

anonymous · Answer

hmmmm..how will i get the force?/

anonymous · Answer

$$P=\frac{F}{A}$$
Solve for F:
$$F=PA$$

F=(1599.868)(pi*10^(-14))

anonymous · Answer

where did this came from? 10^(-14) ?

anonymous · Answer

That should be-4, not -14

The radius is 1cm=10^(-2)m

radius^2 = 10^(-4)

anonymous · Answer

ahhhhhhh..i seee

anonymous · Answer

so it can be l;ike this,, .01^2...right?

anonymous · Answer

yeah :)

anonymous · Answer

I got the answer ! after getting the answer to that?:)

anonymous · Answer

I'd say you're done

anonymous · Answer

ahhh!!!! you're so great !!

anonymous · Answer

Make sure you write out what you did, if this is getting turned in.

anonymous · Answer

yeah,,i did !!