A particle moves along a closed trajectory. Which of the following is always true?

A car travels 60 km in 2 hours and then 40 km in 1 hour. What is its average speed for the entire journey?

Two trains are moving with equal speed in opposite directions along two parallel railway tracks.

If the wind is blowing with speed ‘u’ along the track so that the relative velocities of the trains with respect to the wind are in the ratio $1:2$ then the speed of each train must be

A particle moves along a spiral path given by $r = at$, $heta = bt$, where $a$ and $b$ are constants and $t$ is time. What is the magnitude of average velocity from $t=0$ to $t=T$?

If an object returns to its starting point, what is its displacement?

The motion of a particle is described by the equation $x = a + b{t^2}$, where a=15 cm and b=3 $cm/{s^2}$ Its instantaneous velocity at time 3 sec will be

The velocity of particle is $v = {v_0} + {\rm{g}}t + f{t^2}.$. If its position is x=0 at t=0, then its displacement after unit time (t=1) is

A car moves a distance 200 m. It covers first half of the distance at speed $60\,\,km{h^{ - 1}}$ and the second half at speed v. If the average speed is $40\,\,km{h^{ - 1}}$. The value of v is

A train covers one-third of its journey at speed $v$, the next one-third at speed $2v$, and the final one-third at speed $3v$. Calculate the train's average speed for the entire journey.

Two boys are standing at the ends A and B of a ground where AB=a. The boy at B starts running in a direction perpendicular to AB with velocity ${v_1}$. The boy at A starts running simultaneously with velocity v and catches the other boy in a time t, when t is

The length of second’s hand in a watch is 1 cm. The change in velocity of its tip in 15 seconds is