A-LEVEL Physics: 4.1.18, 4.1.19, 4.1.20: Momentum 2 (Seneca) Flashcards
What are ‘Inelastic Collisions’?
Inelastic Collisions are Collisions where:
-Kinetic Energy is Not Conserved.
-Momentum is Conserved.
What are ‘Elastic Collisions’?
Elastic Collisions are Collisions where:
-Kinetic Energy is Conserved.
-Momentum is Conserved.
What is the Difference Between Elastic & Inelastic Collisions?
-Elastic Collisions Conserve Kinetic Energy.
-Inelastic Collisions Do Not Conserve Kinetic Energy.
-Momentum is Conserved in Both.
In Elastic Collision, ___ ___ & ___ are ___.
Kinetic Energy, Momentum.
In Inelastic Collision, ___ ___ is ___ ___, but ___ is ___.
Kinetic Energy, Not Conserved.
Momentum, Conserved.
In Elastic Collision, Momentum Before = …
Momentum After
In Elastic Collision, Kinetic Energy Before = …
Kinetic Energy After
In Inelastic Collision, Momentum Before = …
Momentum After
In Inelastic Collision, what is Not Conserved?
Kinetic Energy.
How is Kinetic Energy Lost during Inelastic Collision?
Kinetic Energy is Dissipated to the Surroundings, to Stores eg Heat (Thermal) & Sound.
Conservation of Momentum:
Momentum Before = Momentum After
An Explosion is Simply a Collision in ___.
Reverse.
Explosions are ___ Processes. Why?
Inelastic.
Because the Kinetic Energy of the System Always Increases.
Since Ke Before x= Ke After, it is an Inelastic Process.
Inelastic Processes aren’t Always a Loss of Kinetic Energy. It Could Also be…
A Gain in Kinetic Energy.
After an Explosion, where does the Kinetic Energy of the Fragments come from?
The Internal Energy of the System.
What is Needed to Cause an Object with a Lot of Momentum to Come to a Sudden Stop? Why?
A Large Force.
Because of the Change in Momentum.
Cars have Safety Features Such as…
What do they do?
Seat Belts, Air Bags, Crumple Zones.
They Absorb the Kinetic Energy of the Collision, if the Car Crashes.
How is a Seat Belt helpful in the event of a Car Crash?
It Increases the Time Over which the Change in Momentum Occurs, therefore Significantly Reducing the Force that Acts on the Person.
(remember, that large force is the one needed to bring a moving object with lots of momentum to come to a sudden stop)
How are Air Bags & Crumple Zones helpful in the event of a Car Crash?
When the Car Crashes, they Absorb Lots of the Energy by Deforming themselves.
These Features Reduce Injuries to the People in the Car by Absorbing Energy when they Change Shape.
(remember, in elastic deformation, such as this, the Kinetic Energy is Transferred to Surrounding Stores. so the air bags and crumple zones deform, & absorb a significant amount of the energy, that would otherwise harm the person.)
