CIE A Level Physics 1.1 Physical Quantities & Units

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Questions and Answers

What is the SI base unit for force, expressed in terms of the base units?

kg m s

kg m2 s–2

kg m s–2 (correct)

kg s–2

Which of the following correctly expresses the Joule in terms of SI base units?

kg m2 s–1

kg m s–1

kg m2 s–2 (correct)

kg m s–3

The unit Pascal is defined in terms of which basic quantities?

kg/s m2

N/m2 (correct)

kg m2/s2

N/m

How can you determine if a physical equation is homogeneous?

By checking that the units on both sides are the same. Signup and view all the answers

If a derived unit is expressed as kg m–1 s–2, what is the physical quantity represented?

Pressure Signup and view all the answers

Which of the following derived units is correctly matched with its definition?

Newton defined as mass times acceleration Signup and view all the answers

Which expression represents the Joule when breaking it down into SI base units?

kg (m s–1)2 Signup and view all the answers

What must all physical quantities include to be properly defined?

A numerical magnitude and a unit Signup and view all the answers

Which of the following units is incorrectly matched with its corresponding physical quantity?

Voltage - mA Signup and view all the answers

How would a physical quantity represented by the letter 'v' indicate velocity?

It requires additional context to be meaningful Signup and view all the answers

Which of the following describes the relationship between physical quantities and their respective units?

Units provide the necessary context for meaning in physical quantities Signup and view all the answers

Which statement about estimating physical quantities is true?

Knowing common physical quantities is beneficial for estimation Signup and view all the answers

What is the standard mass of an adult used in calculations?

70 kg Signup and view all the answers

Which of the following is NOT one of the SI Base Units required for this course?

Lumen Signup and view all the answers

What is the gravitational field strength used for calculations?

10 m s-2 Signup and view all the answers

Which derived unit would be appropriate for measuring force?

Newton Signup and view all the answers

What is the typical mass of a car used in estimates?

1500 kg Signup and view all the answers

Which base unit corresponds to the quantity of length in the SI system?

Meter Signup and view all the answers

Which wavelength range corresponds to visible light?

400 nm to 700 nm Signup and view all the answers

What is the primary benefit of using SI base units?

They are officially recognized worldwide. Signup and view all the answers

What does the base unit 'second' measure in the SI system?

Time Signup and view all the answers

Which of the following represents a derived unit in physics?

Cubic meter Signup and view all the answers

Study Notes

CIE A Level Physics 1.1 Physical Quantities & Units

Physical quantities are measured using a numerical magnitude and a unit.
Examples include speed, velocity, and volume.
Speed and velocity are physical quantities; speed is the rate of travel along a path, velocity is the rate of change of position in a specific direction
Physical quantities are represented by letters of the alphabet
Units give context to what the letters refer to - if a letter is used to represent velocity, the unit would be meters per second (m/s).
All physical quantities must contain a numerical value and unit.

1.1.2 SI Units

SI units are the internationally recognized system of measurement.
There are seven base units: kilogram (kg), meter (m), second (s), ampere (A), kelvin (K), mole (mol), and candela.

1.1.3 Homogeneity of Physical Equations & Powers of Ten

Physical equations must be homogeneous, meaning the units on both sides of the equation must be the same
To check for homogeneity, the units of each term in an equation are substituted for the variables and are calculated,
If the units on either side are not the same, the equation needs correction
Powers of ten are used to represent very large or very small numbers.
Prefixes like kilo (10³), mega (10⁶), giga (10⁹), tera (10¹²) and micro (10⁻⁶), nano (10⁻⁹)and pico(10⁻¹²) are used to represent these powers of ten.

1.1.4 Scalars & Vectors

Scalars have only magnitude (size). Examples include distance, speed, mass, time, energy, volume, density, pressure, and temperature.
Vectors have both magnitude and direction. Examples include displacement, velocity, acceleration, force, momentum.
Vectors can be combined using triangle or parallelogram methods.
To combine vectors using the triangle method: link the vectors head-to-tail. The resultant vector connects the tail of the first vector to the head of the last.
To combine vectors using the parallelogram method: link the vectors tail-to-tail. The resultant vector is the diagonal of the parallelogram.
Vector subtraction involves reversing the direction of one vector and following the same procedure as vector addition using the triangle or parallelogram method.
In equilibrium, coplanar forces form closed vector triangles, implying the sum of the forces is zero.
Vectors can be resolved into components to simplify calculations involving multiple forces or directions. The horizontal component of a given vector is Fx = F cosθ. The vertical component is Fy = F sinθ.

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Description

Explore the fundamental concepts of physical quantities and units as per the CIE A Level Physics curriculum. This quiz covers topics such as SI units, the importance of units in equations, and the distinction between speed and velocity. Test your understanding of these essential physics concepts.