Here is the complete solution of Chapter 1 **Scientific Study** of Class 10 based on the curriculum of the Nepal Government. Before heading toward the solution, you must read **Chapter 1 Scientific Study Guide**, which we published earlier. Hope this complete grade 10 science solution of Chapter 1 will help you. We will also publish solutions for all the other Chapters.

We are going to solve the exercise part of Chapter Scientific Study. If you don’t have the textbook of Science and Technology for class 10, You can find it **here**.

## Scientific Study – Grade 10 Science Solution Chapter 1 Exercise

This is the exercise of Chapter 1- the scientific study of class 10, whose syllabus is based on the Curriculum Development Center, Nepal Government. We’ve tried to solve the exercise with other additional questions, which might be beneficial for your SEE examination point of view.

### 1. Choose the Right Answers to the Following Questions:

The right answers are ticked. We request you to try by yourself first and check your results by comparing them with ours.

**a. Which of the following is a fundamental unit?**

i. Newton

ii. Pascal

iii. Kilogram**(✓)**

iv. Joule

**b. Which of the following physical quantity has unit m s ^{−1}**?

i. Acceleration

ii. Speed**(✓)**

iii. Force

iv. Density

**c. Which of the following is a derived unit?**

i. Candela

ii. Ampere

iii. Joule**(✓)**

iv. Kelvin

**d. Which of the following group of fundamental units represents the derived unit Newton (N) of Force?**

i. Kgms^{-2}**(✓)**

ii. Kgm^{2}s^{-2}

iii. Kgm^{-2}s^{-2}

iv. Kgms^{−1}

### 2. Give Reason:

**a. The unit of work (Joule )is a derived unit.**

**Ans. **We know, **Work = Force ✕ Displacement**. Here unit of force is **Newton(N)** and the unit of displacement is **meter(m)**, so the unit of work **Joule = N ✕m.** Newton (N=Kgms^{-2}) itself is a derived unit, which depends upon other fundamental units Kg, m, and S. Thus, Joule (J) is a derived unit.

**b. We must Control Some Variables in Scientific experiments.**

**Ans.** We must control some variables in scientific experiments because these variables affect the accuracy of the experiments and if we don’t control these variables, we can’t get an accurate relationship between dependent and independent variables.

**c. Equation v ^{2} =ut is invalid**

**and doesn’t exist**.

**Ans.** For the validity of the equation, the units of the fundamental quantities on both sides must be the same or matched. Here, the fundamental unit of quantity on the left-hand side is m/s and the right-hand side is ms/s = m, which do not match with each thus the equation is invalid and doesn’t exist.

### 3. Difference Between:

**a. Independent and Dependent Variables**

S.N. | Independent Variables | S.N | Dependent Variables |

1. | Values of independent Variables do not depend upon any other variable. | 1. | The values of dependent variables depend upon the independent variables. |

2. | Independent Variables can be changed by the user doing the experiment/research. | 2. | Dependent Variables cannot be changed by the user performing the experiment. It changes with respect to the independent variables. |

3. | It is the cause of change of dependent variables. | 3. | It is the effect of the change of independent variables. |

**b. Fundamental and Derived Units**

S.N | Fundamental Units | S.N | Derived Units |

1. | Independent of other units and have their specific identity. | 1. | Dependent upon the fundamental units and are derived from them. |

2. | Units of fundamental quantities are called fundamental units. | 2. | Units of derived quantities are called derived units. |

3. | There are only 7 fundamental units. | 3. | Units of derived quantities are called derived units. |

### 4. Answer the Following Questions:

**Q1. What is a unit?**

**Ans.** Unit is a known standard quantity with reference to which other unknown physical quantities are measured. Examples: Kg, m, Second, Joule, Pascal, etc.

**Q2. Write the units of mass, temperature, power, and density.**

**Ans. ** The unit of mass is Kilogram(Kg), the temperature is Kelvin (K), the power is Pascal (pa) and the density is Kg/m^{3}. *(Note: All these units are in the SI system of units.)*

**Q3. How is the uniformity of units in the equation checked?** **Clarify your answer with an example.**

**Ans.** The uniformity of units in the equation is measured by checking the fundamental units involved in both sides of the equation.

For example, we need to check the uniformity of units/ validity of the equation in the equations=v*t, the fundamental unit of the left-hand side is ‘m’ and the right-hand side is m*s/s =m which is the same. Thus this equation is a valid equation. This shows the uniformity/ homogeneity of units in the equation.

**Q4. Write fundamental units involved in the unit of pressure.**

** Ans.** We know the unit of pressure is Pascal (Pa), which can also be written as (N/m^{2}). Newton is also a derived unit which is written as (kg*m/s^{2}). So, the fundamental units involved in the unit of pressure are Kilogram(Kg), Meter(m), and Second (S).

**Q5. Find out the fundamental units involved in given derived units.**

a.Newton = kg*m/s^{2} (Kg, m,s)

b. Joule = N*m =kg*m^{2}/s^{2}(Kg, m,s)

c. Watt = J/s = Kg*m^{2}/s^{2}*s(Kg,m,s)

d. Pascal = N/m^{2} =(Kg*m/s^{2})/m^{2} (Kg, m,s)

**Q6. Niva Claimed that the formula for power is P=mv ^{2} and Pressure is P=mv/A. Check the validity of the formula by analyzing the unit.**

Solution:

For Formula P=mv^{2} |

Analyzing the left-hand side of the formula P=mv ^{2}, Here, Power= work done/time workdone=force*displacement so, power=(force*displacement)/time =(kg*m/s ^{2}*m)/s =Kg*m ^{2}/s^{3}Analyzing the right-hand side of the formula P=mv ^{2},Here, mv ^{2} =mass*velocity^{2} =kg*(m/s) ^{2} Here, the unit of LHS and the unit of RHS are not equal. Therefore the formula is invalid. |

^{2}

For Formula P=mv/A |

Analyzing the left-hand side of the formula P=mv/A Pressure= Force/ Area =(kg*m/s ^{2}) /m^{2} =kgm/m ^{2} s^{2} Again, analyzing the right-hand side of the formula P=mv/A Here, mv/A=mass*volume/A =(kg*m ^{3})/m^{2}Here, fundamental units on both sides are not equal, so this formula is also invalid. |

**Q7. Explain types of Variables with examples.**

There are usually 3 types of variables in scientific research. They are independent, dependent, and controlled variables. An example illustrating the slingshot experiment is described to help you understand the concept of variables.

For more detailed information on variables and their types, with examples, read Scientific Study Guide Class 10. You can also know about examples of variables in a scientific study by reading the answer to question 8.

**Q8. Karma used a few pieces of wire to light a pair of lights on a dry cell. He wanted to know how the thickness of the wire affects the lifespan of the dry cell. In the test, he will perform, distinguish the independent, dependent, and controlled variables.**

Ans. Independent Variable: Thickness of wireDependent Variable: Lifespan of dry cell Controlled Variable: Pair of lights, length of wire |

**Question No. 9**, **Question No. 10,** and **Question No. 11** are tasks for students to solve. Comment your answer. If you face any difficulty while solving, you can comment. We will help you.

**Q12. Prove that unit of electrical resistance is the ohm (Ω)=kgm ^{2}s^{-3} A^{-2}**

Solution,

Given Unit of **Ω**=**kgm ^{2}s^{-3} A^{-2}**

where ohm**(Ω**) is the unit of resistance R. From Ohm’s law, V=IR

So, R=V/l

where,

V=Voltage(V)

I=Current

R=Resistance

Expressing ohm in terms of fundamental units.

**Ω**= V/A

where V( volt ) is the unit of electric potential i.e. voltage and A ( Ampere is the unit of current)

Now, **Ω**=J/CA (Volt= Joule/Coulomb)

**Ω**=kg*m^{2}*A^{2}/s^{2}*s where, (C=Ampere*Second)

=**kg.m ^{2}.s^{-3}.A^{2}** (Hence Proved)

## Important Questions:

**Q.Mention some Important Points to describe the variables in the scientific study**.

**Ans.**

- There must be only one independent variable in one experiment.
- There must be only one dependent variable in one experiment.
- Other variables except independent and dependent variables are controlled during the experiment and are called controlled variables.
- While showing the relationship between any two variables, dependent variables are shown on the y-axis, and independent variables are shown on the x-axis.
- When the relation between two variables is expressed as a mathematical equation, then independent variables are written on the right-hand side, and dependent variables are written on the left-hand side.

## Activities:

Collect different types of daily experiments around you and distinguish the types of variables of scientific study in that experiment.

## Conclusion

After solving this exercise, students can solve problems based on variables and units. If you face any kind of difficulties while solving the problems. You can mail us at info@nepaleseteacher.org. Feedback is highly appreciated.

I need a complete manual of exercise of this book from class 5 to class 10.

Amazing! work sir. I am eagerly waiting for the solutions of upcoming chapters.

it is helpful