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Important questions based on NCERT syllabus for Chapter 13 - Motion and Time:
Question-1: Classify the following as motion along a straight line, circular or oscillatory motion:
- Motion of car on a road.
- Motion of pendulum of the clock.
- Motion of a child on a see-saw
- Motion of train on a straight bridge.
- Motion of your hands while running.
Solution: 1) Straight line
2) Oscillatory motion
3) Oscillatory motion
4) Straight line
5) Oscillatory motion
Question-2: What do you mean by oscillatory motion? Give example and explain its oscillatory motion.
Solution: When an object repeats its motion after every fixed interval of time, the motion of the object is called periodic or oscillatory motion. For example: Pendulum clocks, a device having a string suspended with a fixed point with a bob at bottom is called pendulum. The motion of pendulum starting from one extreme end to another extreme end and back to the first extreme end is called one oscillation. Similarly, the motion of a simple pendulum from its mean position to extreme left and extreme right and back to the mean position is called one oscillation.
Question-3: Rohan covers a distance of 10 km by running with uniform speed of 4.5 km/hr. Sohan runs 1.2 km in 15 minutes. Who runs faster?
Solution: 15 minutes = 15/60 hours = 0.25 hrs
Speed = distance/ time
Speed of Sohan = 1.2/ 0.25 = 4.8 km/hr
Speed of Rohan = 4.5 km/hr
Hence, speed of Sohan is faster than Rohan.