An odometer is an instrument used to measure mileage. A compass is an instrument used to determine direction. Choices a, b, and c are incorrect because none is an instrument

Candle clock and sand glass were used to measure time in ancient time but in modern days, time is measured by stop watch and digital clock.

Distance covered by the car in the given time is $$d = 57336.0 - 57321 = 15.0 \ km$$

An object covering equal distances in equal time interval, i.e. moving with a uniform speed  is said to be in a uniform motion. 

Electronic stopwatch, stop clock, pendulum clock and hour glass are the instruments used for measuring the time. Among the following, electronic stopwatch has the highest level of accuracy whereas hourglass has the lowest level of accuracy in measuring time.

The motion of Christiano Ronaldo in the field, motion of Usain Bolt in the race track and the motion of freely falling body are the examples of non uniform motion whereas motion of earth around the sun is the example of uniform motion.
Thus option C is correct.

Fitbit is used for measuring time nowadays. 

Sundial was the earliest clock made by the Egyptians in year 800 BC to measure time.

$$I$$ :
Speed of train while covering a distance of 240 \ km,    $$u = \dfrac{240}{7} = 34.3 \ km/h$$
Speed of train while covering a distance of 360 \ km,    $$u = \dfrac{360}{6} = 60 \ km/h$$
Thus speed of train changed and hence motion of train is an example of non-uniform motion.
$$II$$ :
Speed of Gopi in the car race remains the same in first, second and third hour.
Thus his motion is an example dof uniform motion.
Correct answer is option B.

Let the speed of the train be $$x\ kmph$$

Speedometer is device that measure the speed of vehicle, at any instant of time i.e measure instantaneous speed. 

Stop clocks and stop watches are generally used to measure time for short intervals while wall clocks are used to measure time for long intervals.

Without initial velocity and acceleration path of the particle cannot be decided. So at a time velocity and acceleration are required to determine the path followed by the particle.

If the scooter is travelling at precisely $$30 km/h$$ in a perfectly straight line.

As we know the speedometer used to measure the speed of vehicle and all the vehicle indicate speed in km/h 

Given that,

Time $$t=2.5\min $$

Distance $$d=2km$$

Now, firstly for half distance

  $$ v=\dfrac{d}{t} $$

 $$ t=\dfrac{d}{v} $$

 $$ t=\dfrac{60\times 60}{40} $$

 $$ t=90\,s $$

Now, total time is

  $$ t=150-90 $$

 $$ t=60\,s $$

Now, the speed is

  $$ v=\dfrac{d}{t} $$

 $$ v=\dfrac{1\times 60}{1} $$

 $$ v=60\,km/h $$

Hence, the speed is $$60 km/h$$

	$$LENGTH$$	$$MASS$$	$$TIME$$
$$M.K.S$$	Meter	killogram	sec
$$C.G.S$$	Centi meter	gram	sec
$$S.I.$$	meter	killogram	sec

The unit of time (i.e. second) is the same in all the three systems of units.

Given,

$$speed = \dfrac{distance}{Time}$$

The least count of a wall clock, stop watch, digital watch and atomic clock are $$1 \ sec$$, $$\dfrac{1}{10} \ sec$$, $$\dfrac{1}{100} \ sec$$ and $$\dfrac{1}{10^{11}} \ sec$$ respectively. So atomic clock is most precise.

speed = distance / time