W5 Collisions & Momentum

Question 1

What are the two types of collisions?

Answer 1

1. Elastic Collisions
   - Kinetic energy of the system is conserved. Very uncommon
2. Inelastic Collisions
   - Kinetic energy is transformed into another form of energy

Question 2

What affects the outcome of collisions?

Answer 2

• The mass (kg) of colliding objects

- The velocity (m.s-1) of colliding objects

Question 3

What is the calculation of momentum?
What is the calculation for force?
What is the calculation for impulse?

Answer 3

1. Mass x Velocity = Momentum
Or
m x v = P
2. Mass x change in velocity / change in time = Force
Or 
Change in P / Change in T = Force
3. Force x Time = Impulse
Change in Momentum = Impulse

Question 4

The total momentum of a system = the sum of all the particles in the system
True or False?

Answer 4

True

Question 5

What is Newton’s first law?

Answer 5

• Everything will remain in a state of uniform motion unless changed but an external force.

Question 6

Momentum before the collision = Momentum after the collision
True or False?

Answer 6

True

- We can use this concept to calculate the outcomes of collisions

Question 7

Question:

• Two objects are traveling in opposite directions to collide.
• Object 1 has a mass of 85kg & velocity of 4m.s-1
• Object 2 has a mass of 80kg & velocity of -6m.s-1
• What is the total momentum of the system?
• What is the final velocity of the system?

Answer 7

1. -140 kg.m.s-1
   340kgm.s-1 + -480kgm.s-1
2. 0.85 m.s-1
   VF =Total P/ M1 + M2 = -140/165

Question 8

What is Newtons second law?

Answer 8

• The rate of change of an object is directionally proportional to the resultant force applied and is in the direction of the resultant force.
• When a constant force acts on an object it causes it to accelerate.

Question 9

What does impulse momentum mean?

Answer 9

• Impulse momentum is equal to change in momentum

Question 10

To increase impulse and cause a greater change in momentum we can…

Answer 10

• Increase the force

- Increase the time over which the force was applied

Question 11

Question:

Horizontal impulse = 100N.s and the initial velocity = 3.5m.s-1 what is the final velocity of a runner of mass 70kg?

Answer 11

Impulse = Change in Momentum = Mass x Change in Velocity 
Mass x (IV - FV) = Impulse
70kg x (3.5m.s-1 - FV) = 100N.s
3.5m.s-1 - FV = 100N.s/70kg
FV = 100N.s/70kg + 3.5m.s-1
FV = 4.9m.s-1