$(a)$ Define uniform circular motion.
$(b)$ Ram goes for a morning walk in a circular park daily. He completes one revolution of the park in $4$ minutes. Find his speed if the diameter of the park is $420\, m$.
$(c)$ Draw velocity$-$time graph for uniform motion along a straight line. How can you find distance covered by a body from this graph ?
$(a)$ A body is said to be in uniform circular motion, if it moves along a circular path with constant speed.
$(b)$ Given $t=4$ min $=4 \times 60=240 s , r=210 m$ $v=$
Total distance covered in one revolution
$S=2 \pi r=2 \times 22 / 7 \times 210=1320 m$
Therefore, speed $=$ distance $/$ time
$=1320 / 240=5.5 m s ^{-1}$
$(c)$ The graph is as shown
.Area under the velocity$-$time graph gives the distance covered by an object.
When is the acceleration $(i)$ positive $(ii)$ negative ?
If the displacement of an object is proportional to square of time, then the object moves with
A hiker rides $700\, m$ north, $300$ meast, $400 \,m$ north $600\, m$ west, $1200\, m$ south, $300\, m$ east and finally $100\, m$ north. Draw the path of motion of the biker. What distance did he cover ? What was his displacement ?
Give an expression for the speed of an athlete if he takes time $'t^{\prime}$ to go around a circular track, of radius ${ }^{\prime} r^{\prime}$
A girl walks along a straight path to drop a letter in the letterbox and comes back to her initial position. Her displacement-time graph is shown in Fig. Plot a velocity - time graph for the same.