Answer:
The kinetic energy of the system after the collision is 9 J.
Explanation:
It is given that,
Mass of object 1, m₁ = 3 kg
Speed of object 1, v₁ = 2 m/s
Mass of object 2, m₂ = 6 kg
Speed of object 2, v₂ = -1 m/s (it is moving in left)
Since, the collision is elastic. The kinetic energy of the system before the collision is equal to the kinetic energy of the system after the collision. Let it is E. So,

E = 9 J
So, the kinetic energy of the system after the collision is 9 J. Hence, this is the required solution.
To solve this problem it is only necessary to apply the kinematic equations of angular motion description, for this purpose we know by definition that,

Where,
Angular Displacement
Angular Acceleration
Angular velocity
Initial angular displacement
For this case we have neither angular velocity nor initial angular displacement, then

Re-arrange for 

Replacing our values,


Therefore the ANgular acceleration of the mass is 
The answer is D. <span> There would be a decrease in the population of marine organisms.
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Answer:
0m/s²
Explanation:
Given parameters:
Initial velocity of the boat = 8m/s
Final velocity = 8m/s
Time taken = 4s
Unknown:
Acceleration of the boat = ?
Solution:
Acceleration is the rate of change of velocity with time.
It is mathematically expressed as;
A =
A is the acceleration
v is the final velocity
u is the initial velocity
t is the time taken
Insert the parameters and solve;
A =
= 0m/s²