A-LEVEL Physics: 4.1.18, 4.1.19, 4.1.20: Momentum 2 (Seneca)

Question 1

What are ‘Inelastic Collisions’?

Answer 1

Inelastic Collisions are Collisions where:
-Kinetic Energy is Not Conserved.
-Momentum is Conserved.

Question 2

What are ‘Elastic Collisions’?

Answer 2

Elastic Collisions are Collisions where:
-Kinetic Energy is Conserved.
-Momentum is Conserved.

Question 3

What is the Difference Between Elastic & Inelastic Collisions?

Answer 3

-Elastic Collisions Conserve Kinetic Energy.

-Inelastic Collisions Do Not Conserve Kinetic Energy.

-Momentum is Conserved in Both.

Question 4

In Elastic Collision, ___ ___ & ___ are ___.

Answer 4

Kinetic Energy, Momentum.

Question 5

In Inelastic Collision, ___ ___ is ___ ___, but ___ is ___.

Answer 5

Kinetic Energy, Not Conserved.
Momentum, Conserved.

Question 6

In Elastic Collision, Momentum Before = …

Answer 6

Momentum After

Question 7

In Elastic Collision, Kinetic Energy Before = …

Answer 7

Kinetic Energy After

Question 8

In Inelastic Collision, Momentum Before = …

Answer 8

Momentum After

Question 9

In Inelastic Collision, what is Not Conserved?

Answer 9

Kinetic Energy.

Question 10

How is Kinetic Energy Lost during Inelastic Collision?

Answer 10

Kinetic Energy is Dissipated to the Surroundings, to Stores eg Heat (Thermal) & Sound.

Question 11

Conservation of Momentum:

Answer 11

Momentum Before = Momentum After

Question 12

An Explosion is Simply a Collision in ___.

Answer 12

Reverse.

Question 13

Explosions are ___ Processes. Why?

Answer 13

Inelastic.
Because the Kinetic Energy of the System Always Increases.
Since Ke Before x= Ke After, it is an Inelastic Process.

Question 14

Inelastic Processes aren’t Always a Loss of Kinetic Energy. It Could Also be…

Answer 14

A Gain in Kinetic Energy.

Question 15

After an Explosion, where does the Kinetic Energy of the Fragments come from?

Answer 15

The Internal Energy of the System.

Question 16

What is Needed to Cause an Object with a Lot of Momentum to Come to a Sudden Stop? Why?

Answer 16

A Large Force.
Because of the Change in Momentum.

Question 17

Cars have Safety Features Such as…
What do they do?

Answer 17

Seat Belts, Air Bags, Crumple Zones.
They Absorb the Kinetic Energy of the Collision, if the Car Crashes.

Question 18

How is a Seat Belt helpful in the event of a Car Crash?

Answer 18

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)

Question 19

How are Air Bags & Crumple Zones helpful in the event of a Car Crash?

Answer 19

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.)