# Measurement of Density and Speed Class-7th Study Question Goyal Solutions

Measurement of Density and Speed Class-7th Study Question Goyal Solutions . We Provide Step by Step Answers Study questions of Chapter-1,Physical Quantities and Measurement unit -3 (Measurement of Density and Speed ) Visit official Website  for detail information about ICSE Board Class-7.

## Measurement of Density and Speed Class-7th Goyal Brothers

Physics Solutions Ch-1 (unit-3)

 Board ICSE Class 7th Subject Physics Book Name Goyal Brothers Theme-1 Physical Quantities and Measurement Unit-3 Measurement of Density and Speed Topic Solution of Study Questions with Numericals Session 2023-24

### STUDY QUESTIONS

(Goyal Brothers Physics Solutions Chapter-1 Unit -3)

#### Question 1. You are provided with a piece of rock and common laboratory equipment. How will you proceed to find its density? Diagrams not required.

Answer: Density = mass / volume.

mass of the given rock piece is measured using physical balance.

Let us take a measuring jar and fill water in it partially.

By immersing the given rock piece in measuring jar using a piece of thread,  we can measure the displaced volume of water.

This displaced volume is the volume of given piece of rock.

By knowing mass and volume, we can  calculate its density

#### Question 2. Briefly describe how you will find experimentally the density of milk with a density bottle.

Answer: A density bottle is any bottle of known volume which can be weighed empty and then weighed containing the liquid whose density you wish to determine. Then density = mass/volume and you thus determine density

Measure the mass of density bottle using physical balance. let it be M1.
2. Fill the density bottle upto the volume mark with the milk.
3. Measure the mass of milk+density bottle with physical balance. let it be M2.
4. density = Mass/Volume = (M2-M1) / V

#### Question 3. How does the density of a gas change with the rise in its temperature?

Answer: There is a decrease in density of a gas when increase in the temperature because the intermolecular space between the gas molecules is increased as a result volume increases and density decreases.

#### Question 4. On the basis of change of density with the change in temperature, explain how do the liquids get heated up, when heated in a vessel.

Answer: According to the Thermal Properties Of Matter, when we heat a liquid in a beaker the liquid close to the bottom of beaker (closer to the source of heat) expands and hence its density decreases This lighter water (hot) rise up in the beaker allowing the heavy, dense cold water to take its place towards the base of the beaker causing convection current This current ultimately heats the entire liquid.

#### Question 5. How does the density of gases change with the rise in temperature?

Answer: When a liquid or gas is heated, the molecules move faster, bump into each other, and spread apart. Because the molecules are spread apart, they take up more space. They are less dense. The opposite occurs when a liquid or gas is cooled.

#### (b) State units of density briefly.

Answer: Density is the amount of mass in a unit volume of a substance, this means that in one unit volume of substance how much mass is present.

Common units for density include g/mL, g/cm3, g/L, kg/L, and even kg/m3.

#### Question 7. Describe conversion of the units of density in CGS system and SI system by giving an example.

Answer:  he SI unit of kilogram per cubic metre (kg/m3) and the cgs unit of gram per cubic centimetre (g/cm3) are probably the most commonly used units for density. 1,000 kg/m3 equals 1 g/cm3. (The cubic centimeter can be alternately called a millilitre or a cc.) 10^-3 is the conversion factor between the two units

Question 8.

(a) What do you mean by speed?

Answer: Speed is defined as the rate of change of position of an object in any direction. Speed is measured as the ratio of distance to the time in which the distance was covered

(b) State units of speed briefly.

Answer: The most common speed units are meters per second m/s and kilometres per hour km/h.

#### Question 9. Describe uniform speed with an example.

Answer: When an object travels an equal amount of distance in an equal amount of time then it is moving with a uniform speed. For example, a truck moving on a highway covers equal distances in equal time intervals regardless of the direction of motion of the truck.

#### Question 10. Describe non-uniform speed with an example.

Answer: A body is said to have non-uniform motion if its velocity changes with time. Such a body is necessarily under the influence of an external force. An example of non-uniform motion is a body rotating at a constant speed. Its velocity is not constant because its direction of motion changes every instant.

### Numerical Based Question

(Goyal Brothers Physics Solutions Chapter-1 Unit -3)

(a) gcm-3

(b) kgm-3

(a) gcm-3

(b) kgm-3