The SI unit of electric current is MCQ with Answer and Explanation
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Question #1
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The time period of oscillation of a spring-mass system in a satellite orbiting Earth is:
Correct Answer: Option C
Explanation:
Spring-mass period T = 2π√(m/k), depending only on mass and spring constant, not on gravity. In orbit, apparent weightlessness doesn't affect spring force (which depends on displacement, not gravity). Thus period remains unchanged. Pendulum period would change (depends on g), but spring-mass does not. Memory aid: 'Spring period: independent of g; pendulum period: depends on g'. This conceptual question tests oscillations fundamentals, frequently examined in competitive exams. Always distinguish gravity-dependent (pendulum) from gravity-independent (spring-mass) oscillators.
Spring-mass period T = 2π√(m/k), depending only on mass and spring constant, not on gravity. In orbit, apparent weightlessness doesn't affect spring force (which depends on displacement, not gravity). Thus period remains unchanged. Pendulum period would change (depends on g), but spring-mass does not. Memory aid: 'Spring period: independent of g; pendulum period: depends on g'. This conceptual question tests oscillations fundamentals, frequently examined in competitive exams. Always distinguish gravity-dependent (pendulum) from gravity-independent (spring-mass) oscillators.
Question #2
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A block of mass 10 kg is accelerating at 2 m/s^2 on a horizontal surface under an applied force of 50 N. What is the magnitude of the frictional force opposing its motion?
Correct Answer: Option D
Explanation:
According to Newton's Second Law, the net force on the block is F_net = mass * acceleration = 10 kg * 2 m/s^2 = 20 N. The net force is the difference between the applied forward force and the opposing frictional force (F_net = F_applied - F_friction). So, 20 N = 50 N - F_friction. Solving for friction gives F_friction = 50 - 20 = 30 N.
According to Newton's Second Law, the net force on the block is F_net = mass * acceleration = 10 kg * 2 m/s^2 = 20 N. The net force is the difference between the applied forward force and the opposing frictional force (F_net = F_applied - F_friction). So, 20 N = 50 N - F_friction. Solving for friction gives F_friction = 50 - 20 = 30 N.
Question #3
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The half-life of a substance is 2 years. After 6 years, what fraction of original substance remains?
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