Answer:
The correct option is;
(a) High power density
Explanation:
The power density of a material is the amount of power per unit volume of the material. Power density, in the context of transformers, fuel cells, batteries, motors, and power supply units, is measured with respect to the volume, and the units is given as W/m³
A system such as a capacitor with an high power density has the capacity to put out large energy amount from a small volume. A capacitor with a high power density, can produce the same power output as a car battery and is said to have a high power density.
because not all substances react the same to temperature changes. If you heat a metal and an organic substance and you turn the temperature up, the organic substance like water will react (boil) while most metals need higher temperature to react.
Answer:
The diameter is 50mm
Explanation:
The answer is in two stages. At first the torque (or twisting moment) acting on the shaft and needed to transmit the power needs to be calculated. Then the diameter of the shaft can be obtained using another equation that involves the torque obtained above.
T=(P×60)/(2×pi×N)
T is the Torque
P is the the power to be transmitted by the shaft; 40kW or 40×10³W
pi=3.142
N is the speed of the shaft; 250rpm
T=(40×10³×60)/(2×3.142×250)
T=1527.689Nm
Diameter of a shaft can be obtained from the formula
T=(pi × SS ×d³)/16
Where
SS is the allowable shear stress; 70MPa or 70×10⁶Pa
d is the diameter of the shaft
Making d the subject of the formula
d= cubroot[(T×16)/(pi×SS)]
d=cubroot[(1527.689×16)/(3.142×70×10⁶)]
d=0.04808m or 48.1mm approx 50mm
