In which of the following scenarios is the work done physically zero? MCQ with Answer and Explanation
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Question #1
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A body weighs 72 N on the surface of the Earth. What is the gravitational force on it at a height equal to half the radius of the Earth?
Correct Answer: Option B
Explanation:
Weight on surface W = mg = 72 N. Acceleration due to gravity at height h is g' = g [R / (R+h)]². Here h = R/2. So, g' = g [R / (R + R/2)]² = g [1 / (3/2)]² = g (2/3)² = 4g/9. The new weight W' = mg' = m(4g/9) = (4/9)mg = (4/9) × 72 = 32 N.
Weight on surface W = mg = 72 N. Acceleration due to gravity at height h is g' = g [R / (R+h)]². Here h = R/2. So, g' = g [R / (R + R/2)]² = g [1 / (3/2)]² = g (2/3)² = 4g/9. The new weight W' = mg' = m(4g/9) = (4/9)mg = (4/9) × 72 = 32 N.
Question #2
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The number of significant figures in the measurement 0.0050200 m is:
Correct Answer: Option A
Explanation:
According to the rules of significant figures, leading zeros (0.00) are never significant as they only indicate the position of the decimal point. However, trailing zeros after a decimal point are always significant. Therefore, in 0.0050200, the significant digits are 5, 0, 2, 0, and 0, making a total of 5 significant figures.
According to the rules of significant figures, leading zeros (0.00) are never significant as they only indicate the position of the decimal point. However, trailing zeros after a decimal point are always significant. Therefore, in 0.0050200, the significant digits are 5, 0, 2, 0, and 0, making a total of 5 significant figures.
Question #3
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A car moving at constant velocity of 10 m/s has net force acting on it equal to
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