A wire gets heated when it is bent back and forth. Why?

Why does a wire get heated when it is bent back and forth ?

When a beam is bent

Tea gets cooled, when sugar is added to it. Why ?

A wire is 4 m long and has a mass 0.2 kg. The wire is kept horizontally. A transverse pulse is generated by plucking one end of the taut (tight) wire. The pulse makes four trips back and forth along the cord in 0.8 sec. The tension is the cord will be -

State if the motion is transverse, longitudinal or a combination of both. Wave produced in a cylinder containing water by moving its piston back and forth.

A wire when bent in a shape of equilateral triangle encloses area of 726 sq units.Find the area when the wire is bent in the shape of the circle

to get one's own back

Why do the brake drums of a car get heated, when the car moves down a hill at a constant speed?

A wire of certain length carries a steady current. It is first bent to form a circular wire of one turn. The same wire is bent to form a circular coil of three turns. The ratio of magnetic induction at the centre of the coil in the two cases is ________