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Answers
(c)Negative acceleration is called retardation. If the velocity of a body is decreasing with respect to time, the acceleration is said to be negative. Examples of retardation motion are: 1) Velocity of vehicle decreases when brake is applied.
Q-3(a)Every unit of length has a corresponding unit of area, namely the area of a square with the given side length. Thus areas can be measured in square kilometres, or km2.
(B)The newton (symbol: N) is the International System of Units (SI) derived unit of force. It is named after Isaac Newton in recognition ofJoule
(c)Joule, unit of work or energy in the International System of Units (SI); it is equal to the work done by a force of one newton acting through one metre. Named in honour of the English physicist James Prescott Joule, it equals 10^7ergs, or approximately 0.7377 foot-pounds
(D)The pascal (symbol: Pa) is the SI derived unit of pressure used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is defined as one newton per square metre and is equivalent to 10 barye (Ba) in the CGS system.
(E)Watt is the SI unit of power, equivalent to one joule per second.
Power = force × velocity = Work/time
So, watt=Nms
−1
=J/s
Q-4.A seconds pendulum is a pendulum whose period is precisely two seconds; one second for a swing in one direction and one second for the return swing, a frequency of 0.5 Hz.
Q-5.The time period of the simple pendulum depends upon the length of the pendulum and also to some extent it depends upon the degree of the amplitude. That is the width of the pendulum's swing. In general, the time period of a pendulum means one complete cycle that is one complete left swing and right swing