Question

(a) What do you mean by percussion instrument? Give two examples.
(b) State the energy change (i) Electrical cell in a circuit (ii) petrol engine of running car (iii) burning of wood.

Answer 1

Hint:This question consists of two segments, one which refers to the definition of percussion instrument and its examples of other energy change. Energy is defined as the ability to do work. Energy is converted into different forms to make use of them.

Complete answer:
Let us understand what percussion instrument refers to: a percussion instrument is a musical instrument which keeps on vibrating or produces sound when it is struck by a stick or other instrument prepared only for its use, by rubber bands or by hands.

Percussion instruments are also sub-divided into two categories as idiophones and membranophones.Idiophones are those substances which vibrate to produce their own sound. Whereas, membranophones produce sound with the help of a stretched membrane.Two examples of percussion instruments are bass drum and bell.

Let us now come to the second part of the question to define the energy change in these substances:
(i) Electrical cell in a circuit- An electrical cell also known as a battery is composed of cathode, anode and a medium to transport charges. In this type of cell, the chemical energy of the cell is changed to electrical energy.
Chemical energy\[ \to \] Electrical energy

(ii) petrol engine in a running car- The petrol inside the engine burns to produce energy. Hence, we can say, chemical energy is converted to heat energy. Then the heat energy after the combustion of fuel in the engine, helps to drive the car or develop kinetic energy.
Heat energy$ \to $ Kinetic Energy

(iii) Burning of a wood
It can be said that the potential energy stored in the wood gets converted to heat energy for various purposes. Also, combustion is actually a chemical process where the electrons get excited and hence produces heat energy.
Potential chemical energy$ \to $ Heat energy

Note:It must be noted that there is an elaborate method of changing energy. It does not happen directly as stated in the answer. There are various more changes during the process, the significant ones are reflected in the answer. For example, while burning wood the energy changes to heat energy and light energy too. There is also some chemical energy also produced in this process, but the amount of heat energy liberated is more, so we consider it as significant.