Answer:
The rate at which the container is losing water is 0.0006418 g/s.
Explanation:
- Under the assumption that the can is a closed system, the conservation law applied to the system would be:
, where
is all energy entering the system,
is the total energy leaving the system and,
is the change of energy of the system. - As the purpose is to kept the beverage can at constant temperature, the change of energy (
) would be 0. - The energy that goes into the system, is the heat transfer by radiation from the environment to the top and side surfaces of the can. This kind of transfer is described by:
where
is the emissivity of the surface,
known as the Stefan–Boltzmann constant,
is the total area of the exposed surface,
is the temperature of the surface in Kelvin,
is the environment temperature in Kelvin. - For the can the surface area would be ta sum of the top and the sides. The area of the top would be
, the area of the sides would be
. Then the total area would be 
- Then the radiation heat transferred to the can would be
. - The can would lost heat evaporating water, in this case would be
, where
is the rate of mass of water evaporated and,
is the heat of vaporization of the water (
). - Then in the conservation balance:
, it would be
. - Recall that
, then solving for
:
Answer:
a) u = 30.29 m/s
b) t = 2.09 s
Explanation:
given,
velocity = 45 m/s
angle (θ) = 50°
horizontal velocity = 45 cos 50°
time taken to reach 150 m.
times = 
t = 5.19 s
a) height of arrow



s = 46.78 m
v² - u² = 2 g s
u² = 2 × 9.81 × 46.78
u = 30.29 m/s
b) time taken by the apple = 
= 3.09 s
time after which it has to be thrown = 5.19-3.09 = 2.1 s
Answer:
W = 8.92 10² kJ
Explanation:
For this exercise they give us the strength, we must calculate the distance traveled, for this we need the rocket acceleration let's use Newton's second law
F = m a
a = F / m
a = 20 103/1400
a = 14.29 m/s²
With kinematics we can find the distance traveled
² = v₀² + 2 a x
x = (
²-v₀²) / 2 a
x = (50² -35²) / 2 14.29
x = 1275 / 28.58
x = 44.61 m
Let's calculate the work
W = F.d
The bold is vector; as indicated by the force is in the direction of movement the scalar product is reduced to the ordinary product
W = F d
W = 20 10³ 44.61
W = 8.92 10⁵ J
W = 8.92 10² kJ