An artificial satellite is moving in a circular orbit of radius nearly $42.250 \,km .$ Calculate its linear velocity, if it takes $24$ hour to revolve round the earth.
Given $r=42.250 km , T =24$ hours $=86400 s$
The linear velocity is given by the expression
$v=\frac{2 \pi r}{ T }=\frac{2 \times 3.14 \times 42250}{86400}=3.07 \approx 3.1 km s ^{-1}$
Give an expression for the speed of an athlete if he takes time $'t^{\prime}$ to go around a circular track, of radius ${ }^{\prime} r^{\prime}$
By giving an example, prove that rest and motion are relative terms.
The slope of the line on a position-time graph reveals information about an object's velocity. What conclusion can you draw regarding the motion of an object, if the graph is a
$(i)$ Horizontal line.
$(ii)$ Straight diagonal line.
$(iii)$ Curved line.
Diagram shows a velocity$-$time graph for a car starting from rest. The graph has three sections $A B$, $B C$ and $C D$
$(i)$ From a study of this graph, state how the distance travelled in any section is determined.
$(ii)$ Compare the distance travelled in section $BC$ with distance travelled in section $A B$.
$(iii)$ In which section car has zero acceleration ?
$(iv)$ Is the magnitude of acceleration higher or lower than, that of retardation ? Give reason.
What is the relation between distance and time
$(i)$ when body is moving with uniform velocity ?
$(ii)$ when body is moving with variable velocity ?