Two movers use a rope system to lift a box to a third-story apartment. they do 1,200 j of work on the rope system, and the rope
2 answers:
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Answer:
(a) Steel rod:
Copper rod:
(b) Steel rod:
Copper rod:
Explanation:
Length of each rod = 0.75 m
Diameter of each rod = 1.50 cm = 0.015 m
Tensile force exerted = 4000 N
(a) Strain is given as the ratio of change in length to the original length of a body. Mathematically, it is given as
Strain =
where Y = Young modulus
F = Fore applied
A = Cross sectional area
For the steel rod:
Y = 200 000 000 000
F = 4000N
A = (r = d/2 = 0.015/2 = 0.0075 m)
=> A =
=> A = 0.000177
∴
For the copper rod:
Y = 120 000 000 000 N/m²
F = 4000N
A = (r = d/2 = 0.015/2 = 0.0075 m)
=> A =
=> A = 0.000177
(b) We can find the elongation by multiplying the Strain by the original length of the rods:
Elongation = Strain * Length
For the steel rod:
Elongation =
For the copper rod:
Elongation =
The heat required to convert the unknown substance X from one phase to another is 1600 J times the specific heat of that substance.
Explanation:
The heat energy required to convert a substance or to heat up or increase the temperature of a substance can be obtained from the specific heat formula.
As per this formula, the heat energy applied should be equal to the product of mass of the substance with temperature gradient and also with specific heat of the substance. Basically, the heat provided to increase or convert a substance should be more than the specific heat of the substance.
Since, here the mass of the substance X is given as m = 20g and the temperature change is given from -10°C to 70°C.
Then ΔT = (70-(-10))=70+10=80°C.
As the substance is unknown, the specific heat of that substance can also not be determined. Hence keep it as C.
Q = 1600C J
Thus, the heat required to convert the unknown substance X from one phase to another is 1600 J times the specific heat of that substance.