The root mean square value of alternating current is defined as the equivalent DC current that produces the same: MCQ with Answer and Explanation
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Question #1
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An engine pumps water continuously through a hose. Water leaves the hose with a velocity 'v' and mass per unit length is 'm'. What is the power imparted to the water?
Correct Answer: Option A
Explanation:
Power is the rate of doing work or imparting kinetic energy (dK/dt). Mass exiting per second = m * v (mass/length * length/time). Kinetic energy imparted per second = 1/2 * (mass per second) * v^2 = 1/2 * (mv) * v^2 = 1/2 * m * v^3. This is a very common advanced mechanics question.
Power is the rate of doing work or imparting kinetic energy (dK/dt). Mass exiting per second = m * v (mass/length * length/time). Kinetic energy imparted per second = 1/2 * (mass per second) * v^2 = 1/2 * (mv) * v^2 = 1/2 * m * v^3. This is a very common advanced mechanics question.
Question #2
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A gap is left between railway tracks to allow for
Question #3
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The mode of heat transfer that can occur in vacuum is:
Correct Answer: Option A
Explanation:
Radiation transfers heat via electromagnetic waves and requires no medium, thus works in vacuum (e.g., solar energy reaching Earth). Conduction needs direct contact between particles; convection requires fluid movement. Vacuum lacks matter for conduction/convection. Memory tip: 'Radiation = only mode in vacuum'. This fundamental distinction is frequently tested in competitive exams. Applications include thermos flasks (minimizing all three modes) and space technology. Always recall that radiation speed is light speed, while conduction/convection are much slower.
Radiation transfers heat via electromagnetic waves and requires no medium, thus works in vacuum (e.g., solar energy reaching Earth). Conduction needs direct contact between particles; convection requires fluid movement. Vacuum lacks matter for conduction/convection. Memory tip: 'Radiation = only mode in vacuum'. This fundamental distinction is frequently tested in competitive exams. Applications include thermos flasks (minimizing all three modes) and space technology. Always recall that radiation speed is light speed, while conduction/convection are much slower.
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