A body of mass 2 kg is moving with an acceleration of 5 m/s². The rate of change of its momentum is:
A. 2.5 N
B. 10 N
C. 10 kg m/s
D. 0.4 N
Answer: Option B
Solution (By JKSSB Mock Tests)
According to Newton's Second Law of Motion, the rate of change of momentum is directly proportional to the applied unbalanced force. Rate of change of momentum = Force = mass × acceleration. Force = 2 kg × 5 m/s² = 10 Newtons (N). Note that '10 kg m/s' is a unit of momentum, not its rate of change.
Explanation:
A geostationary satellite must appear stationary to an observer on the Earth's surface. To achieve this, it must orbit in the exact equatorial plane and strictly follow the Earth's rotation. Since the Earth rotates on its axis from West to East, the geostationary satellite must also orbit from West to East.
Explanation:
Three significant figures require the number to be written with three meaningful digits. 3.00 × 10⁸ m/s has three significant figures (3,0,0). 3 × 10⁸ has one significant figure; 3.0 × 10⁸ has two; 300000000 has ambiguous significance. Standard scientific notation: 3.00 × 10⁸ m/s. This is important in precision measurements.
A student measures the length of a rod as 3.50 cm using a vernier caliper with least count 0.01 cm. The number of significant figures in this measurement is:
Explanation:
The measurement 3.50 cm has three significant figures. All non-zero digits (3,5) are significant, and the trailing zero after the decimal point is also significant as it indicates precision of the measuring instrument. The least count of 0.01 cm confirms that the measurement is precise to hundredths place. Significant figures reflect measurement reliability. Exam tip: Trailing zeros after decimal are always significant; leading zeros are never significant. This concept is crucial for error analysis in experimental physics questions.
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