The document explains the concept of levers as simple machines with a rigid beam and fulcrum, describing three classes of levers based on the position of effort, load, and fulcrum. It also discusses waves as disturbances that transfer energy through a medium, classifying them into types such as mechanical and electromagnetic waves, as well as the motion of waves. Additionally, it covers terms related to wave properties and provides example problems to calculate wave parameters such as frequency and wavelength.

1. LEVERS

2. A lever is a simple machine made of a rigid beam and a
fulcrum. The effort (input force) and load (output force) are
applied to either end of the beam.
In a lever the effort is applied to overcome a resistive force
called a load.
In other words a lever is any device that turns about a fulcrum
or pivot.
Lever

3. 1st class levers
In a first class lever, the
fulcrum is located between
the load and the effort.
Classes of lever

4. 2nd class levers
In a second class
lever, the load is
located between the
effort and the fulcrum.
Classes of lever

5. In a third class
lever, the effort is
located between the
load and the
fulcrum.
If the fulcrum is closer
to the load, then less
effort is needed to
move the load
Classes of lever

6. What type of levers are the following pictures showing ?

7. WAVES

8. What are waves?
A wave can be described as:
A disturbance that travels through a medium
from one location to another location,
accompanied by a transfer of energy.
Or
A disturbance which enables information and
energy to move from one point to another without
the need for a material object to travel the
distance.
All waves carry energy.

9. What is medium in terms of waves?
Definition:
A medium is the substance through which a wave can propagate.
Water is the medium of ocean waves. Air is the medium through which we hear sound
waves. The electric and magnetic fields are the medium of light. Earth is the medium
of seismic waves (earthquake waves). Cell membranes are the medium of nerve
impulses. Transmission lines are the medium of alternating current electric power.

10. Classification of waves
1) By type
2) By motion of the particle
3) By the motion of the wave form

11. By Type
1) A Mechanical Wave-Waves that exist in a material medium and require the medium for propagation.
Example : Water wave, string or spring waves, sound waves
One most familiar with
2) Electromagnetic waves- require no material medium to exist or to propagate. Can travel through a
vacuum.
Examples: light, radiant heat,radio waves
Always have the same speed in a vacuum
3) Matter wave: Waves associated with atomic particles e.g electrons, protons and other fundamental
particles.

12. By motion of the wave form
1) Travelling wave- if the wave form moves from one point to another then the wave is a
travelling wave.
We can further discuss between a pulse and a wave train
a) Pulse : a single disturbance which moves through the medium.
b) Wave train: Continuous. A wave consisting of cycles or patterns that are repeated.
2) Standing wave: if the wave form appears to be stationary, i.e, you do not see a propagating wave
it is called a standing wave.
Now that we have been introduced to waves let’s apply some Physics.

13. By Motion of particles
Consider a mechanical wave on a string or on a spring when the wave
( disturbance) is created and sent through the medium, the displaced
particles of the medium will move about their mean positions as the wave
travels through the medium.
Waves can oscillate in two ways with regards to the motion of disturbance.
1) Transverse waves:
2) Longitudinal wave

14. Transverse waves
These are waves in which the direction of oscillation (movement of the
particles) is perpendicular to the direction of wave travel.
For example:
- water waves
- light waves
- electromagnetic waves

15. Longitudinal wave
Sound is a mechanical
vibration in a medium
which travels outward
from a source as
longitudinal waves.

16. Let’s now look at some important terms
to understand.
Crest : is the peak of the transverse wave.
Trough: the lowest point of the transverse wave.
Compression: particles that are the closest for a
longitudinal wave.
Rarefaction: particles that are the furthest apart in a
longitudinal wave.
Oscillate: the direction of the to and fro motion
Travel/ Propagation: the direction in which the
waves move from start to finish.

17. Longitudinal and Transverse Waves

20. Waves Equation
v = fλ
v- speed of the wave
f- frequency of the wave
λ-wave length

21. Waves Equation

22. PRACTICE
Calculate the wavelength of the broadcast from a radio station which emits
waves of frequency 104.1 MHz, given that the speed of the wave is 3.0 x 108
m/s

23. PRACTICE
A water wave has a speed of 3.0 m/s and its crests are 5.0 m apart. It
approaches a reef at an angle of incidence of 60°. On passing over it, the
distance between its crests reduces to 4.0 m.
Determine for the wave:
a the frequency in the deeper water
b the period in the deeper water
c the frequency as it passes over the reef (shallow)
d the period as it passes over the reef
e the speed as it passes over the reef
f the angle of refraction on reaching the reef
g the refractive index on travelling from the deep to the shallow.

25. Describing a wave
Progressive waves can be represented by two
different kinds of graph.
1. A displacement position graph
2. A displacement time Graph

26. Describing a wave- Displacement- position graph
Displacement- position graph
A displacement- position graph
represents the position of all the
particles in a wave at a fixed time
during its movement.
https://youtu.be/CVsdXKO9xlk?s
i=K60x__erKrINZC0p

27. Describing a wave- Displacement- time
graph
This graph shows the
behaviour of a single
particle over a period of
time. It shows how the
displacement of a
particle changes as a
wave passes

28. .

29. Figure 19.14 shows a wave of speed 40 m/s.
Determine:
a the amplitude of particle P
b the displacement of particle P
d the frequency
e the wavelength

30. Figure 19.13 shows a wave of speed 32 m/s at an
instant in time. Determine:
a the amplitude
b the wavelength
c the frequency
d the period