Answer:
c. because A will land first becuase its heavier :)
Explanation:
 
        
             
        
        
        
Distance is 90km,time 1 hr
distance 2 is 82km,time 5 hrs
average speed=total distance travelled/total time taken.
90+82=172/5+1=6
average speed=28.7km over hour
        
             
        
        
        
Answer:
160N/m
Explanation:
According to Hooke's law which states that the extension of an elastic material is directly proportional to the applied force provided that the elastic limit is not exceeded. Mathematically,
F = ke where 
F is the applied force 
k is the spring constant
e is the extension
From the formula k = F/e
Since the body accelerates when the block is released, F = ma according to Newton's second law of motion.
The spring constant k = ma/e where 
m is the mass of the block = 0.4kg
a is the acceleration = 8.0m/s²
e is the extension of the spring = 2.0cm = 0.02m
K = 0.4×8/0.02
K = 3.2/0.02
K = 160N/m
The spring constant of the spring is therefore 160N/m
 
        
             
        
        
        
The speed of sound in fresh water is 1482m/s. 
It says ocean floor, so we should a little bit more accurate, and use the fact that the speed of sound in salt water (that has no bubbles) is 1560m/s. 
speed = distance / time 
Therefore Distance = speed x time = 1560 x 3.3 = 5158m 
The sonar wave is sent out by the boat, reflected off the seafloor, and then is received back at the boat on the surface. So the distance 5148m is the distance from the boat to the sea bottom and then back up to the boat again. 
So the depth of the water is half this distance Depth of water = 5148/2=2574m
        
             
        
        
        
Radial fractures tend to occur first when a pane of glass is struck.
Answer: Option A 
<u>Explanation:</u>
There is a slight difference between radial and concentric fractures and as radial fractures are formed which extends outwards in a radial manner  from the point where the glass is struck. 
Whereas concentric fractures are circular in pattern and they terminate long before radial crack. Also when a bullet is fired from a gun, a similar reaction is observed as it gets struck on the surface and fractures are formed in the same pattern.