17 Researchers have developed a new type of filament lamp with an efficiency of 40%. Old-typefilament lamps have an efficiency of 5.0%. The two types of lamp produce the same useful outputpower.What is the ratio input power to new type of lampinput power to old type of lamp ?A 0.13 B 0.63 C 1.6 D 8.018 A student attempts to derive the formula for kinetic energy EK . She begins by considering anobject of mass m which is initially at rest. A constant force F applied to the object causes it toaccelerate to final velocity v in displacement s. The kinetic energy gained by the object is equal tothe work done on the object by the force F.Which equation would the student not need in order to derive the formula for EK ?A F = ma B W = Fs C E = Fs21 D v 2 = u 2 + 2as19 A metal wire obeys Hooke’s law and has a Young modulus of 2.0 10 11 Pa. The wire has anoriginal length of 1.6 m and a diameter of 0.48 10 –3 m.What is the spring constant of the wire?A 7.2 10 3 N m–1B 2.3 10 4 N m–1C 2.9 10 4 N m–1D 9.0 10 4 N m–120 A wire is being stretched by a tensile force.Which statement about the elastic limit must be correct?A The deformation is plastic after the elastic limit has been reached.B The deformation is plastic until the elastic limit is reached.C The extension is proportional to the tensile force after the elastic limit has been reached.D The extension is proportional to the tensile force until the elastic limit is reached.21 Which statement is correct for all types of progressive wave?A The distance from a peak to the next trough is equal to a wavelength.B They can be demonstrated in ripple tanks.C They consist of vibrating atoms.D They transfer energy from one position to another
Question
17 Researchers have developed a new type of filament lamp with an efficiency of 40%. Old-typefilament lamps have an efficiency of 5.0%. The two types of lamp produce the same useful outputpower.What is the ratio input power to new type of lampinput power to old type of lamp ?A 0.13 B 0.63 C 1.6 D 8.018 A student attempts to derive the formula for kinetic energy EK . She begins by considering anobject of mass m which is initially at rest. A constant force F applied to the object causes it toaccelerate to final velocity v in displacement s. The kinetic energy gained by the object is equal tothe work done on the object by the force F.Which equation would the student not need in order to derive the formula for EK ?A F = ma B W = Fs C E = Fs21 D v 2 = u 2 + 2as19 A metal wire obeys Hooke’s law and has a Young modulus of 2.0 10 11 Pa. The wire has anoriginal length of 1.6 m and a diameter of 0.48 10 –3 m.What is the spring constant of the wire?A 7.2 10 3 N m–1B 2.3 10 4 N m–1C 2.9 10 4 N m–1D 9.0 10 4 N m–120 A wire is being stretched by a tensile force.Which statement about the elastic limit must be correct?A The deformation is plastic after the elastic limit has been reached.B The deformation is plastic until the elastic limit is reached.C The extension is proportional to the tensile force after the elastic limit has been reached.D The extension is proportional to the tensile force until the elastic limit is reached.21 Which statement is correct for all types of progressive wave?A The distance from a peak to the next trough is equal to a wavelength.B They can be demonstrated in ripple tanks.C They consist of vibrating atoms.D They transfer energy from one position to another
Solution
This seems like a series of physics questions. Let's answer them one by one:
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The ratio of input power to the new type of lamp to the input power to the old type of lamp is calculated by dividing the efficiency of the old lamp by the efficiency of the new lamp. So, 5.0% / 40% = 0.125 or 0.13 when rounded to two decimal places. So, the answer is A 0.13.
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To derive the formula for kinetic energy (EK = 1/2 mv^2), the student would need to use the equations F = ma and W = Fs. However, the equation E = Fs is not necessary for this derivation. So, the answer is C E = Fs.
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The spring constant (k) of a wire can be calculated using the formula for Young's modulus (Y = stress/strain = (F/A) / (ΔL/L)). Rearranging this formula gives us k = (F/ΔL) = YA/L. Given that Y = 2.0 x 10^11 Pa, A = π*(0.48 x 10^-3 m/2)^2, and L = 1.6 m, we can substitute these values into the formula to find k.
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The statement about the elastic limit that must be correct is D. The extension is proportional to the tensile force until the elastic limit is reached. After the elastic limit, the deformation becomes plastic and is no longer proportional to the force applied.
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The correct statement for all types of progressive wave is D. They transfer energy from one position to another. This is the fundamental characteristic of waves.
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