CBSE ADDA: sample paper science class 9th sa2 solved:
1. Relative density of silver is 10.8. The density of water is 103 Kgm-3. What is the density of silver in SI unit?
Ans: Relative density of silver = 10.8 Relative density of water = 103 Kgm-3
Density of silver = Relative density of silver x Relative density of water = 10.8 x 103 Kgm-3
2. Is potential energy a vector or a scalar quantity?
Ans: Potential energy is a scalar quantity.
3. (i) Give any two examples of longitudinal waves.(ii) What is the most essential property of a wave motion and why?
Ans: (a) i. Waves produced in air. ii. When a freely suspended spring is pulled downwards and released, longitudinal waves are produced.
(b) The most essential property of a wave motion is its frequency. Frequency of a wave is its inherent characteristic and does not change by the change in temperature, pressure or change in medium.