1.1. To answer the question To answer the question “What is Damping?”“What is Damping?”

Book Reference : Pages 45-46Book Reference : Pages 45-46

What equipment do cars or bikes tend to have What equipment do cars or bikes tend to have to iron out the bumps in the road?to iron out the bumps in the road?

If the car suspension consisted only of If the car suspension consisted only of springs, what would happen to the motion springs, what would happen to the motion of the car for sometime after hitting a bump of the car for sometime after hitting a bump in the road?in the road?

How would a pendulum continue to swing in How would a pendulum continue to swing in an “ideal physics world” with no friction and a an “ideal physics world” with no friction and a vacuumvacuum

What do we observe in the “real-world”What do we observe in the “real-world”

Most vehicles use springs or similar to iron out Most vehicles use springs or similar to iron out the lumps and bumpsthe lumps and bumps

With only springs the vehicle will continue to With only springs the vehicle will continue to bounce (oscillate up and down) for some time bounce (oscillate up and down) for some time after hitting the bump and the passengers after hitting the bump and the passengers would feel sea sick. Think SHM!would feel sea sick. Think SHM!

Pendulum would keep going with full amplitude Pendulum would keep going with full amplitude for everfor ever

Friction and air resistance reduce the Friction and air resistance reduce the amplitude until eventually the pendulum stopsamplitude until eventually the pendulum stops

Shock absorbers (dampers)

Shock absorbers (dampers)

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

What will the ride in the car be like whenWhat will the ride in the car be like when

1.1. The damping is not strong enoughThe damping is not strong enough

2.2. The damping is too strongThe damping is too strong

3.3. The damping is just rightThe damping is just right

No bears, kitchen furniture, porridge or small girls with golden No bears, kitchen furniture, porridge or small girls with golden hair were harmed in the making of this lessonhair were harmed in the making of this lesson

1.1. Light damping (under damping)Light damping (under damping)

2.2. Heavy damping (over damping)Heavy damping (over damping)

3.3. Critical dampingCritical damping

1.1. Light damping (under damping) The Light damping (under damping) The oscillation slowly dies away (exponential oscillation slowly dies away (exponential decay). Oscillations slowly die awaydecay). Oscillations slowly die away

2.2. Heavy damping (over damping) The Heavy damping (over damping) The damping is so strong that the displaced damping is so strong that the displaced object takes a long time to return to the object takes a long time to return to the equilibrium position and does not oscillateequilibrium position and does not oscillate

3.3. Critical damping : just enough to stop the Critical damping : just enough to stop the oscillation as quickly as possible often about oscillation as quickly as possible often about T/4 little or no overshootT/4 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?