There is a circular pond and foot-path runs along its boundary. A man walks around it, exactly once, keeping close to the edge. If his step is 66 cm long and he takes exactly 400 steps to go around the pond, what is the diameter of the pond?

A circular pond has a 90cm wide footpath along the edge.A man walk around the outer edge of the footpath with 66cm long steps.In 400 steps he makes a full round.What is the radius of the pond.

A stationary, circular wall clock has a face with a radius of 15cm. Six turns of wire are wound around its perimeter, the wire carries a current 2.0 A in the clockwise direction. The clock is located, where there is a constant, uniform external magnetic field of 70 mT (but the clock still keeps perfect time) at exactly 1 : 00 pm, the hour hand of the clock points in the direction of the external magnetic field What is the magnitude of this torque.