4.80-kg bucket of water is accelerated upward by a cord of negligible mass whose breaking strength is 75.0 N. If the bucket star
ts from rest, what is the minimum time required to raise the bucket a vertical distance of 12.0 m without breaking the cord?
2 answers:
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Answer:
The amount of thermal energy needed is 15167500 joules.
Explanation:
By First Law of Thermodynamics, we see that amount of thermal energy (), in joules, is equal to the change in internal energy. From statement we understand that change in internal energy consisting in two latent components (
,
), in joules, and two sensible component (
), in joules, that is:
(1)
By definitions of Sensible and Latent Heat, we expanded the formula:
(2)
Where:
- Mass, in kilograms.
- Latent heat of fussion of water, in joules per kilogram.
- Latent heat of vaporization of water, in joules per kilogram.
- Specific heat of ice, in joules per kilogram per degree Celsius.
- Specific heat of water, in joules per kilogram per degree Celsius.
- Change in temperature of ice, measured in degrees Celsius.
- Change in temperature of water, measured in degrees Celsius.
If we know that ,
,
,
,
,
and
, then the amount of thermal energy is:
The amount of thermal energy needed is 15167500 joules.
The De Broglie wavelength of the electron is
And we can use De Broglie's relationship to find its momentum:
Given
, with m being the electron mass and v its velocity, we can find the electron's velocity:
This velocity is quite small compared to the speed of light, so the electron is non-relativistic and we can find its kinetic energy by using the non-relativistic formula:
And we can use De Broglie's relationship to find its momentum:
Given
This velocity is quite small compared to the speed of light, so the electron is non-relativistic and we can find its kinetic energy by using the non-relativistic formula:
Answer:
, where the minus indicates the direction is opposite to that of the throw.
Explanation:
a)
Since MKS stands for meter-kilogram-second and we know that:
We can write that:
These are conversion factors, equal to 1, so multiplying our results by them won't change their value, only their units.
So we have that:
b)
Newton's 2nd Law tells us that F=ma, and the definition of acceleration is , so we have:
Taking the throw direction as the positive one, for our values we have: