Answer:
Torque = 0.25Nm
Explanation:
To calculate the magnitude of torque, first we must calculate the lever arm. The lever arm is perpendicular distance from the axis of rotation to the line of the action of the force.
Lever arm = r sin theta
Where r = 4.9cm= 0.049m
Theta = 30°
Lever arm = 0.049 sin30° = 0.245m
Magnitude of torque = rfsintheta
f = 1.0T
Magnitude of torque= 0.245×1.0 = 0.245Nm
To 2 significant figure=0.25Nm
Answer:
Given:
Th = 270 °C = 270+273 = 543 K, hot temperature
Tc = 210 °C = 210+273 = 363 K, cold temperature
According to the Carnot theorem, the maximum efficiency achievable by a heat engine between a hot and cold temperature is
η = 1 - Tc/Th
= 1 - 363/543
= 0.668 = 11.047 (approx)
Answer: 11.0% (nearest integer)
When particles in a substance slow down, we can infer that the object is getting colder. Why we can infer this:
1. Kinetic energy, is energy due to motion, therefore if there is no motion, there is no kinetic energy.
2. The colder an object get, the closer it becomes to having it's particles stopping completely, eventually at the absolute zero.
3. As kinetic energy increases, particles move faster. Kinetic energy usually increases when an object gets warmer. As kinetic energy decreases, particles move slower. Kinetic energy usually decreases when an object gets colder.
So, with this information, we now how and why the kinetic energy slows down.
A line has negative slope if it slopes downward from left to right on a graph.
<span>The maximum possible efficiency, i.e the efficiency of a Carnot engine , is give by the ratio of the absolute temperatures of hot and cold reservoir.
η_max = 1 - (T_c/T_h)
For this engine:
η_max = 1 - [ (20 +273)K/(600 + 273)K ] = 0.66 = 66%
The actual efficiency of the engine is 30%, i.e.
η = 0.3 ∙ 0.664 = 0.20 = 20 %
On the other hand thermal efficiency is defined as the ratio of work done to the amount of heat absorbed from hot reservoir:
η = W/Q_h
So the heat required from hot reservoir is:
Q_h = W/η = 1000J / 0.20 = 5000J</span>