Sample:
As soon as the lightning is seen, sound travels in the air for several kilometers until it eventually reaches the observer.
        
             
        
        
        
a) 32 kg m/s
Assuming the spring is initially at rest, the total momentum of the system before the collision is given only by the momentum of the bowling ball:

The ball bounces off at the same speed had before, but the new velocity has a negative sign (since the direction is opposite to the initial direction). So, the new momentum of the ball is:

The final momentum after the collision is the sum of the momenta of the ball and off the spring:

where  is the momentum of the spring. For the conservation of momentum,
 is the momentum of the spring. For the conservation of momentum,

b) -32 kg m/s
The change in momentum of bowling ball is given by the difference between its final momentum and initial momentum:

c) 64 N
The change in momentum is equal to the product between the average force and the time of the interaction:

Since we know  , we can find the magnitude of the force:
, we can find the magnitude of the force:

The negative sign simply means that the direction of the force is opposite to the initial direction of the ball.
d) The force calculated in the previous step (64 N) is larger than the force of 32 N.
 
        
             
        
        
        
Answer:
D. Frozen water is less dense than liquid water.
Explanation:
Titanic sank in the North Atlantic Ocean in the year 1912. There were more than 2000 passengers on board from which about 1500 died. 
Frozen water that is ice has less density than liquid water. The density of ice is  and the density of the water is
 and the density of the water is  .
. 
Due to this very slight difference in density, ice floats on water. Titanic, on the night of April 14, 1912, crashed into an iceberg around midnight which caused opening of 5 of its watertight compartments. The water filled into the ship and it eventually sank in. 
 
        
             
        
        
        
Answer:
72km
Explanation:
30 mins --> 30 x 60 s = 1800 s
Distance --> Speed x Time 
 = 40m/s x 1800s
 = 72 000 m
 = 72 km (1km is 1000m)
 
        
             
        
        
        
Answer:
I think its C, even with the typo.