Book Reference : Pages 45-46
1.
To be able to answer the question “What is
Damping?”

What equipment do cars or bikes tend to have to iron out the bumps in the road?
If the car suspension consisted only of springs, what would happen to the motion of the car for sometime after hitting a bump in the road?
How would a pendulum continue to swing in an “ideal physics world” with no friction & in a vacuum
What do we observe in the “real-world”

Most vehicles use springs or similar to iron out the lumps and bumps
With only springs the vehicle will continue to bounce (oscillate up and down) for some time after hitting the bump and the passengers would feel sea sick. Think SHM!
Pendulum would keep going with full amplitude for ever
Friction and air resistance reduce the amplitude until eventually the pendulum stops

Shock absorbers
(dampers)

Shock absorbers
(dampers) http://www.acoustics.salford.ac.uk/feschools/waves/shm4.htm

In the “real-world” a system in SHM such as a pendulum or a mass on a spring will eventually come to rest due to “losing energy”, actually doing work against friction and air resistance!

What will the ride in the car be like when
1. The damping is not strong enough
2. The damping is too strong
3. The damping is just right
No bears, kitchen furniture, porridge or small girls with golden hair were harmed in the making of this lesson
[VPL Damping]

1. Light damping (under damping)
2. Heavy damping (over damping)
3. Critical damping

1. Light damping (under damping) The oscillation slowly dies away (exponential decay).
2. Heavy damping (over damping) The damping is so strong that the displaced object takes a long time to return to the equilibrium position and does not oscillate
3. Critical damping : just enough to stop the oscillation as quickly as possible often about
T/4 with little or no overshoot

What caused this?
How could it be avoided?

Caravan Stabiliser :
Friction is introduced into the tow mechanism to damp both sideways and up and down motion

1) State is damping is light, critical or heavy in these cases:
A child on a swing, displaced and released
Oil in a U shaped tube displaced from equilibrium and released
2) What would happen if the oil in a damper
(shock absorber) was replaced with very viscous (thick) oil?

1) A family car has an unloaded mass of 1000kg. The mass is supported equally by 4 springs. When fully loaded the total mass increases to 1250kg causing the springs to compress by a further 2cm. When the car hits a bump in the road it bounces. Find the period of these oscillations.
State assumptions
[0.64s]