An engine has an energy input of 125 J, and 35 J of that energy is transformed into useful energy. What is the efficiency of the
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Complete Question:
Find the resistance of a wire of length 0.65 m, radius 0.25 mm and resistivity 3 * 10^{-6} ohm-metre.
Answer:
Resistance = 9.95 Ohms
Explanation:
<u>Given the following data;</u>
Length = 0.65 m
Radius = 0.25 mm to meters = 0.00025 m
Resistivity = 3 * 10^{-6} ohm-metre.
To find the resistance of the wire;
Mathematically, resistance is given by the formula;
Where;
- P is the resistivity of the material.
- L is the length of the material.
- A is the cross-sectional area of the material.
First of all, we would find the cross-sectional area of the wire.
Area of circle = πr²
Substituting into the equation, we have;
Area = 3.142 * (0.00025)²
Area = 3.142 * 6.25 * 10^{-8}
Area = 1.96 * 10^{-7} m²
Now, to find the resistance of the wire;
<em>Resistance = 9.95 Ohms </em>
The appropriate expression for the calculation of power by relating the angular energy in a given time.
In other words the instantaneous power of an angular accelerating body is the torque times the angular velocity
Where
Torque
Angular speed
Our values are given by
The angular velocity must be transformed into radians per second then
Replacing,
The average power delivered by the engine at this rotation rate is 211.1kW