1) The minute hand of a clock is 7 cm long. Calculate the distance covered and the displacement of minute hand of the clock from 9.00 AM to 9.30 AM.
2) An athlete completes a round of a circular track of diameter 200 m in 20s. Calculate the distance travelled by the athlete.
3)A boy is running on a straight road. He runs 500 m towards north in 2 minutes 10 seconds and then turns back and runs 200 m in 1 minute. Calculate his average speed and magnitude of average velocity during the whole journey.
4) Akshil drove his car with speed of 20 km/h while going to his college. When he returned to his home along the same route , the speed of the car is 30 km/h. Calculate the average speed of the car during the entire journey.
1) Radius = 7cm
Distance = Half the Circumference of the circle= 2πr/2= πr= 22/7 x 7= 22 cm
Displacement = Diameter = Twice the radius = 2 x 7 = 14 cm
2) Circumference of a circle = 2πr
Distance travelled by an athlete = 2 x 22/7 x 100 = 628.57 cm
3) average speed = total distance/total time
Total distance = (500 + 200)m = 700m
Total time = (2.10 + 1.00)min =3.10 min =186sec
Average speed = 700/186 = 3.763 m/s
Average velocity = Total displacement from initial position /total time
Displacement = (500 – 200)m = 300m
Time = 3.10min = 186 sec
Average velocity = 300/186 = 1.612 m/s