Solution of practice question based on chapter 1 (physical quantities and Measurement ) for class 7

 1. Four fundamental physical quantities are as follows:

A.length-fixed distance between two points.

   Its SI unit is metre.(m)

B.Mass- quantity of matter contained in a body.

  Its SI unit is kilogram.(kg)

C.Time- interval between two consecutive events.

  Its SI unit is second.(s)

D.Temperature- degree of hotness or coldness of a body.

  Its SI unit is kelvin.(K)

2.No. it is not possible to measure volume of a body by using a graph paper or graphical method because by using graph paper we can find area of a body. Further area and volume are two different physical quantities. So ,Same method cannot be used to find two different physical quantities.

3.Given,

 Base area =150 m²

 height of the table=12m

Total of the table & box = 25m

Volume of the box= ?

Height of the cuboid box= total height - table's height

                                            = 25m - 12m

                                             =13m

Volume of the box= l×b×h  

                                 = area × h

                                 = 150 m² × 13 m

                                  =1950 m³

4. Density of water is maximum at 4 degree Celsius. Density of water decreases when it is cooled from 4 degree Celsius to 0 degree Celsius or heated above 4°C.

Yes. It is going to affect the volume of water.

Density = mass / volume.

Density is inversely proportional to volume.

Since density decreases,so it means volume will increase.

5. Liquid displacement method is a method in which ,we find the volume of an irregular shaped body by putting it in a measuring cylinder which is partially filled with liquid.the object should be completely immersed in liquid.then we note down reading

V = final reading while object is in measuring cyllinder - initial reading of cyllinder without the object.

V = V² - V¹

6. Mercury is used as a barometric substance because its density is more than the density of water.so, height of the Mercury column required to balance the atmospheric pressure is 76 cm but in case of water the height of the water column required will be a 10.34m which is a difficult task to maintain. Hence mercury is preferred as a barometric liquid.