C because...
Models represent objects, events, and processes in the real world.
Models are often used when an object, event, or process
occurs too slowly or too quickly;
is too small or too large;
is too complicated or too dangerous.
The ocean is spreading at such a slow rate that it would take scientists 50 or more years to collect enough meaningful data from the ocean floor to complete a study. Therefore, scientists use models in order to both predict how the floor will keep spreading and to understand what the ocean floor looked like thousands of years in the past.
Explanation:
Given
Range of ball =7.88 m
Initial speed=13.1 m/s
and we know
Range of Projectile is






(b)other angle would be complementary of 

Quantity of electrical charge is measured in Coulombs.
The symbol is C.
b. C
Answer:

Explanation:
Charge on the plates of the capacitor due to transfer of electrons is given as

here we know that

so we have


now we have electric field between the plates is given as

here we have


now we have



Answer:
Half life of S = 3.76secs
Explanation:
The concept of half life in radioactivity is applied. Half life is the time taken for a radioactive material to decay to half of its initial size.
For part 1 - How much signal will be degraded in 1secs = 1/3.9 = 0.2564
for part 2 - How much signal will be degraded in 1secs = 1/104 = 0.009615
Simply say = 1/3.9 + 1/104 = 0.266015
So both part 1 and part 2 took 1/0.266015 = 3.76secs is the half life of S when both pathways are active