Chapter 2 - Foundations Of Physics

Question 1

What are the seven SI base units?

Answer 1

Length - Metre - m
Mass - Kilogram - kg
Time - second - s
Electric Current - ampere - A
Temperature - Kelvin- K
Amount of Substance - mole - mol

Question 2

What are the prefixes for units and what do they mean?

Answer 2

Peta - 10^15
Tera - 10^12
Giga - 10^9
Mega - 10^6
Kilo - 10^3
Deci - 10^-1
Centi - 10^-2
Milli - 10^-3
Micro - 10^-6
Nano - 10^-9
Pico - 10^-12
Femto - 10^-16

Question 3

What are some derived units?

Answer 3

Force - Newtons - kg
Pressure - pascal - Nm^-2
Energy/Work done - joule - Nm
Power - watt - Js^-1
Electric Potential Difference - Volt - J C^-1
Electric Resistance - ohm - =V A^-1
Electric Charge - coulomb - A s
Frequency - Hertz - s^-1

Question 4

What is a scalar quantity?

Answer 4

Has a magnitude but not direction

Question 5

What is a vector quantity?

Answer 5

Has magnitude and direction

Question 6

How is a one dimensional vector represented?

Answer 6

A line with a single arrowhead

Length of line is magnitude (drawn to scale)
Direction is the direction of the vector

Question 7

How do you add parallel and antiparallel vectors?

Answer 7

Parallel - 3N and 4N in the same direction is 3+4= 7N

Antiparallel - 3N and 4N in opposite directions is 3+-4= -1N

Question 8

How do you find the force acting when two vector quantities are at right angles to each other?

Answer 8

Draw a line to represent one vector
Draw another line from the end of the the first to show the other
Use Pythagoras theorem
To find direction use trig

Question 9

How do you resolve a vector into two components?

Answer 9

In the x direction you use Fx = Fcosθ

In the y direction you use Fy = Fsinθ

Question 10

How do you add non perpendicular vectors?

Answer 10

You use the sine and cosine rules

Cosine rule finds the magnitude
Sine rule finds the direction