Answer:
The amount of work required for the heart is: 3.14 Joules
Explanation:
We need to remember that the work done for a pump with constant pressure will be:
, where W is the work, P is pressure and V is volume (change of the volume). Now we need to find the pressure. Using the Pascal's law (
), where P is pressure, p is density, g is the gravity and h is the height of the fluid's column and replacing the values given, we can find the pressure:
. Then using the work's equation and replacing the value obtain for the pressure and the volume we get:
.
Answer:
(A) 0.54 kg.m^{2}
(B) 0.0156 N
Explanation:
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here is the complete question:
A small ball with mass 1.20 kg is mounted on one end of a rod 0.860 m long and of negligible mass. The system rotates in a horizontal circle about the other end of the rod at 5100 rev/min. (a) Calculate the rotational inertia of the system about the axis of rotation. (b) There is an air drag of 2.60 x 10^{-2} N on the ball, directed opposite its motion. What torque must be applied to the system to keep it rotating at constant speed?.
solution
mass of the ball (m) = 1.5 kg
length of the rod (L) = 0.6 m
angular velocity (ω) = 4900 rpm
air drag (F) = 2.60 x 10^{-2} N = 0.026 N
(take note that values from the original question are used, with the exception of the air drag which was not in the original question)
(A) because the rod is mass less, the rotational inertia of the system is the rotational inertia of the rod about the other end, hence rotational inertia =
where m = mass of ball and L = length of rod
= 
= 0.54 kg.m^{2}
(B) The torque that must be applied to keep the ball in motion at constant speed = FLsin90
= 0.026 x 0.6 x sin 90 = 0.0156 N
If she travels for 30 minutes, and goes at 10 kilometers per hour, she travels 5 kilometers.
An hour is 60 minutes. So, to get 30, divide by 2. Just halve it all, and you will get 10 / 2 = 5.
Work = N × m = 50 x 40 = 2000 J
<span>It means that the passage of time changes in different reference frames that are moving relative to each other. </span>
