Available Answers

1. 1.

   Fill in the blanks:

   1. The _____________ was adopted by the General Conference of Weights and Measures in 1960 to confirm the uniformity in measurement.
   2. The substances with higher density has more _____________ per unit volume.
   3. The C.G.S. unit of density is _____________.
   4. Equal volume of different substances have _____________ masses.
   5. The volume of a cube of side 6 cm is _____________ cm³.
   6. The point of _____________ and the surroundings of an object suggest whether it is in motion or at rest.
   7. Beating of heart is an example of _____________ motion.
   8. The weight of a body on the moon is _____________of its weight on the earth.
   9. During a uniform motion, the object has a _____________ speed.
   10. It is due to the _____________ of the vocal cords that the humans speak.
   11. Work done can be expressed as the product of _____________ and _____________.
   12. A moving body possesses _____________ energy.
   13. Potential energy is _____________ proportional to the mass of the object.
   14. As the bob of the simple pendulum starts moving from a point to the mean position, the _____________ energy starts converting to the kinetic energy.
   15. During the process of photosynthesis, the _____________ energy from the sun is utilized.
   16. When the incident ray strikes the reflecting surface normally, ∠i = ∠r =  _____________.
   17. No definite image is in e case of _____________ reflection.
   18. The plane mirror is used by the soldiers for _____________.
   19. Speed of light in vacuum or air is _____________ m/s.
   20. The light coming from the sun is also called the _____________.
   21. The stage where both the bodies have attained the same temperature is known as  _____________.
   22. The stem of thermometer is made up of a thick glass to protect the _____________.
   23. The interval between the freezing point and the boiling point in the Fahrenheit scale is divided into _____________ parts.
   24. The gap is left between two concrete slabs of the cement roads for allowing _____________ of the concrete.
   25. Water at the bottom of the water bodies is _____________ than at the surface.
   26. One compression and one _____________ constitute a wave.
   27. The maximum displacement of a wave on either side of the mean position is defined as the _____________ of the wave.
   28. The surface area of the vibrating body also affects _____________ of the sound produced by it.
   29. The gap between the direct sound and the echo is less than _____________.
   30. The box that does not allow the sound from within to come out and outside sound to enter is called _____________.
   31. The end of the magnet that points towards the geographical north pale is called the
       pole.
   32. The magnetic lines form _____________  curves in a magnetic field.
   33. In an electromagnet, the end in which current flows in the _____________ direction is the north pole.
   34. The strength of a _____________ magnet cannot be changed.
   35. In an electric bell, the armature is connected to the adjustment screw using a _____________ .
2. 2.

   State whether the following statements are true (T) or false (F):

   1. Density = Mass x Volume.
   2. A boy travelling a distance of 180 m in 1 minute, possesses a speed of 3 m/s.
   3. The volume of cuboid is the product of length, breadth and height.
   4. The density of water at 4°C is the minimum.
   5. The S.I. unit of time is minute.
   6. The acceleration due to gravity for the earth is 9.8 m/s².
   7. 1 kgf = 12 N.
   8. A book lying on the table is an example of a body neither at rest nor in motion.
   9. When a ball falls down vertically, its motion is linear.
   10. The weight of a body is measured using a beam balance.
   11. It is possible to transform one form of energy into another form.
   12. The electricity can be obtained from the energy possessed by the flowing water.
   13. It is possible to change the potential energy of an object to the kinetic energy.
   14. In nature, the energy exist only in one form.
   15. Both the work and energy have the Same units.
   16. The image obtained on a plane mirror is smaller than the actual size of the object.
   17. In solar cookers, spherical mirrors are used as reflectors.
   18. Magenta and green are secondary colours.
   19. A blue cellophane paper passes the light of only blue colour through it.
   20. A piece of paper appears white because it reflects light of all the colours.
   21. On heating. the liquids expand much more than the solids.
   22. The transfer of heat takes place until both the bodies have attained the same temperature.
   23. The trapped air is a conductor of heat.
   24. Black and dull surfaces absorb less radiations.
   25. Conduction is the slowest process among conduction, convection and radiation.
   26. Multiple echoes are called reverberation.
   27. Non-metals are good reflectors of sound.
   28. The region where the particles are spread apart are known as the compressions.
   29. The vibrating prongs of the tuning fork produce sound.
   30. The sound energy is produced by a vibrating object.
   31. The connecting wires are usually made up ef copper.
   32. Household wiring is done using the series circuit.
   33. The magnetism of soft iron is permanent in nature and cannot be lost.
   34. The current can flow through an open circuit.
   35. A battery is a combination of cells of the same kind.
3. 3.

   Why are the measuring cylinders made up of plastics and glass?

4. 4.

   1 cm³ block of wood weighs lesser than 1 cm³ block of iron. Explain.

5. 5.

   Explain the terms: rest and motion.

6. 6.

   A bus takes 30 minutes to cover a distance of 15 km. Calculate its speed.