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:
Explanation:
Since the cable touches the road at the mid point of two towers
so here we have vertex at that mid point taken to be origin
now the maximum height on the either side is given as
horizontal distance of the tower from mid point is given as
now from the equation of parabola we have
now we have
now we need to find the height at distance of 200 ft from center
so we have
A :-) for this question , we should apply
F = ma
Given - F = 12 N
a = 0.20 m/s^2
Solution -
F = ma
12 = m x 0.20
m = 12 by 0.20
m = 60 kg
.:. The mass is 60 kg.
Answer:
No temperature change occurs from heat transfer if ice melts and becomes liquid water (i.e., during a phase change). For example, consider water dripping from icicles melting on a roof warmed by the Sun. Conversely, water freezes in an ice tray cooled by lower-temperature surroundings.
Explanation:
Energy is required to melt a solid because the cohesive bonds between the molecules in the solid must be broken apart such that, in the liquid, the molecules can move around at comparable kinetic energies; thus, there is no rise in temperature. Similarly, energy is needed to vaporize a liquid, because molecules in a liquid interact with each other via attractive forces. There is no temperature change until a phase change is complete. The temperature of a cup of soda initially at 0ºC stays at 0ºC until all the ice has melted. Conversely, energy is released during freezing and condensation, usually in the form of thermal energy. Work is done by cohesive forces when molecules are brought together. The corresponding energy must be given off (dissipated) to allow them to stay together Figure 2.
The energy involved in a phase change depends on two major factors: the number and strength of bonds or force pairs. The number of bonds is proportional to the number of molecules and thus to the mass of the sample. The strength of forces depends on the type of molecules. The heat Q required to change the phase of a sample of mass m is given by
Q = mLf (melting/freezing,
Q = mLv (vaporization/condensation),
where the latent heat of fusion, Lf, and latent heat of vaporization, Lv, are material constants that are determined experimentally.
