C is probably the correct one
Answer:
- <u>77.8 m/s, downward</u>
Explanation:
For uniform acceleration motion, the average speed is equal to half the soum of the initial velocity, Vi, and the final velocity, Vf
- Average speed = (Vf + Vi)/2
Also, by definition, the average speed is the distance divided by the time:
- Average speed = distance / time
Then:
Other kinematic equation for uniform acceleration is:
Since the window is falling and the air resistance is ignored, a = g (gravitational acceleration ≈ 9.8m/s²)
Replacing the known values we can set a system of two equations:
From (Vf + Vi)/2 = 300m/6.62s
(Vf + Vi) = 2 × 300m/6.62s
- Vf + Vi = 90.634 equation 1
From Vf = Vi + a×t
Vf - Vi = 9.8 (6.62)
- Vf - Vi = 64.876 equation 2
Adding the two equations:
- Vf = 77.8 m/s downward (velocities must be reported with their directions)
Answer:
h = 1.02 m
Explanation:
This is a fluid mechanics exercise, where the pressure is given by
P =
+ ρ g h
The gauge pressure is
P -
= ρ g h
In this case the upper part of the tube we have the atmospheric pressure. and the diver can exert a pressure 10 KPa below the outside pressure, this must be the gauge pressure
= P - 
= ρ g h
h =
/ ρ g
calculate
h = 10 103 / (1000 9.8)
h = 1.02 m
This is the depth at which man can breathe