Question

A boy is moving in a circle of radius 7 m with constant speed 11m/sec. Magnitude of displacement in 5 sec is​

Answer 1

Circumference of the circle=2πr

= 2×π×7=2×(22/7)×7 =44m

Speed of the boy= 11m/sec

In 5 sec he will cover=55m

So the boy will cover =55/44 =1full circumference and 1/4 of circle

1/4 or 1 quadrant of circle will subtend 90 ° angle at the centre of circle

Let A be start point on the circumference of the circle,B the finish pojnt and O centre of the circle

AO=BO=r = 7 m

Angle AOB=90″

Triangle AO B is a right angle triangle

Thus AB^2=7^2+7^2=2×7^2

A B= (√2)×7 =10 m

Displacement of the boy will be 10 m