Physics in Depth

Model Question Solution Group 'A' 1. A metre rule is used to measure the length of a piece of string in a certain experiment. It is found to be 20 cm long to the nearest millimeter. How should this result be recorded in a table of results? (a) 0.2000 m (b) 0.200 m (c) 0.20 m (d) 0.2 m Explanation: From the question, it is obvious that the least count of the metre scale is 1 mm as it measures upto the millimeter. Since, 1 mm = 0.001 m . So, result should have three significant figures. Thus, \[\begin{align*} 20 cm &= \frac{20}{100}\\ \therefore 20 cm &=0.200 \hspace{0.01cm} m\\ \end{align*}\] 2. Forces are applied to a rigid body. The forces all act in the same plane. In which diagram is the body in equilibrium? (b) Explanation: In this case, the downward force has balanced the upward force and hence the body is in equilibrium. 3. An athlete makes a long jump a