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• Speed – distance covered by object in one unit time
• Uniform motion – motion in which object moves with constant speed
• Non uniform motion – motion in which speed of an object varies
• Average speed – total distance covered by the object, divided by total time taken to cover that distance
• Speed = Distance Time
• Unit of speed – m/s, m/min, km/hr.
• Speedometer – device used to measure speed
• Odometer – device used to measure distance
• Distance = Speed × time
• Simple pendulum – a metallic bob tied to the string of length one meter
• Time period of pendulum – time taken by the bob to complete one oscillation
• Watch complete video on simple pendulum here
• Measurement of time is done by the clock. A clock have a short hand called the hour hand and a long hand called the minute hand. Many clocks also have second hand which is longer than hour hand as well as minute hand. The motion of hour hand is slowest while the motion of second hand is fastest.
• In a full day, the hour hand in 12 hours clock completes 2 revolutions; one revolution before midday and other after midday. The time before midday is expressed with AM, and the time after midday is expressed with PM.To measure time smaller than an hour, there are 5 divisions between neighbouring numbers. Accordingly in 12 hours clock there are 60 divisions. When the minute hand covers 5 divisions, we say that time measured with minute hand is 5 minutes and so on
• 1 minute = 60 seconds
• 1 hour = 60 minutes
• 1 day = 24 hours
• Watch video and learn how to measure time.
• Distance – time graph – Represent change in position of object with respect to time. If object cover equal distances in equal intervals of time, the object is said to be performing uniform motion. For such motion distance-time graph is straight line indicating that distance is directly proportional to time.