Home › SPM Physics › Archive for Introduction to Physics › Page 2

Introduction to Physics

1.2.2.2 Unit of Speed, Density and Pressure

Posted on by

Speed, density and pressure are derived quantities. When converting their units, firstly, we write the units in fraction form, then only do the unit convertion for the numerator and denominator.


Example
1. Complete the following unit conversion of speed.
  1. 90 kmh-1 = __________ ms-1
  2. 110 kmh-1 = __________ ms-1
  3. 1.3 ms-1 = __________ kmh-1
  4. 8.12 ms-1 = __________ kmh-1
Answer:
a.

b.

c.

d.

2. Complete the following unit conversion of density and pressure.
  1. 760 kgm-3 = __________ gcm-3
  2. 12000 kgm-3 = __________ gcm-3
  3. 5.1 gcm-3 = __________ kgm-3
  4. 3600 Nm-2 = __________ Ncm-2
  5. 12x106  Nm-2 = __________ Ncm-2
  6. 1.5x103 Nm-2= __________ Ncm-2
  7. 3.16x10-5 Ncm-2= __________ Nm-2
  8. 7.1x10-3 Ncm-2 = __________ Nm-2

Answer:
a.

b.

c.

d.

e.

f.

g.

h.


 

1.2.2.1 Derived Units

Posted on by

SI unit

  1. The International System of Units (abbreviated SI from the French language name Système International d'Unités) is the modern form of the metric system. 
  2. It is the world's most widely used system of units, both in everyday commerce and in science.

Derived Unit

  1. The derived unit is a combination of base units through multiplying and/or dividing them.
  2. For instance,  Speed is defined as the rate of distance change, and can be written in the mathematic form

Example:
Find the derived unit of density.

Answer:

Unit of Density = kg/m3

 

1.2.2 Derived Quantities

Posted on by
  1. A derived quantity is a Physics quantity that is not a base quantity. It is the quantities which derived from the base quantities through multiplying and/or dividing them.
  2. For example, speed is define as rate of change of distance, Mathematically, we write this as Speed = Distance/Time. Both distance and time are base quantities, whereas speed is a derived quantity as it is derived from distance and time through division.
    Example

    (Speed is derived from dividing distance by time.)
  3. Belows are the derived quantities that you need to know in SPM. You need to know the equation of all the quantities, so that you can derive their unit from the equation.
  4. If you find it difficult to memorise all these equation, you can skip it now because you are going to learn all of them in the other chapter. 

 

1.2.1 Base Quantities

Posted on by

Physical Quantity

  1. A physical quantity is a quantity that can be measured.
  2. A physical quantity can be divided into base quantity and derived quantity.

Base Quantities

  1. Base quantities are the quantities that cannot be defined in term of other physical quantity.
  2. The base quantities and its units are as in the table below:

TIPS: In SPM, you MUST remember all 5 base quatities and its SI unit.  

1.1.1 Understanding Physics

Posted on by

1.1.1 Understanding Physics

Physics is a branch of science that study the

  1. natural phenomena
  2. properties of matter
  3. energy

Field of study in Physcis

The field of studys in Physics including

  1. Motion
  2. Pressure
  3. Heat
  4. Light
  5. Waves
  6. Electricity'
  7. Magnetism and electromagnetism
  8. Electronics
  9. Nuclear Physics