A body can have zero average velocity but not zero average speed. Justify giving an example.
When a body starts moving from a reference point and returns back after sometime, its average velocity is zero but average speed has some magnitude.
Example : After completing a complete rotation on a circular path, the average velocity of an object is zero but its average speed is a ratio of circumference of the path and time taken in traversing it.
$(a)$ Define circular motion.
$(b)$ "Uniform circular motion is an accelerated motion". Justify this statement with reason.
$(c)$ An artificial satellite is moving in a circular orbit of radius $42250\, km.$ Calculate its speed if it takes $24$ hours to revolve once around the earth.
What conclusion can you draw from the displacement$-$time graph of a body as shown below ?
List two differences in tabular form between speed and velocity. When is a body said to have :
$(a)$ uniform velocity and $(b)$ variable velocity. How is the average velocity of a body is calculated when its velocity changes at a non$-$uniform rate ?
In a long distance race, the athletes were expected to take four rounds of the track such that the line of finish was same as the line of start. Suppose the length of the track was $200\, m$.
$(a)$ What is the total distance to be covered by the athletes ?
$(b)$ What is the displacement of the athletes when they touch the finish line ?
$(c)$ Is the motion of the athletes uniform or nonuniform ?
$(d)$ Is the displacement of an athlete and the distance moved by him at the end of the race equal ?
A truck is moving on a straight road with uniform acceleration. The following table gives the speed of the truck at various instants of time.
Speed $\left(m s^{-1}\right)$ | $5$ | $10$ | $15$ | $20$ | $25$ | $30$ |
Time $(s)$ | $0$ | $10$ | $20$ | $30$ | $40$ | $50$ |
Draw the speed-time graph by choosing a convenient scale. Determine from it
$(i)$ the acceleration of truck
$(ii)$ the distance travelled by the truck in $50$ seconds.