Answer:
It will take 4 sec rock to comes its original point
Explanation:
It is given that the rock comes to its original point
So displacement S = 0 m
Initial velocity u = 19.6 m/sec
Acceleration due to gravity 
According to second equation of motion 


t = 4 sec
It is possible, but very slim. The fish will move before the spear goes through its body because the fish will sense danger and feel it hit the water and automatically move
Answer:
B. Conductivity.
Explanation:
Conductivity is the quantity of heat passing per second through a slab of unit cross-sectional area when the temperature gradient between the two faces is unity when put in heat.