You look up the element in the periodic table. Subtract the atomic number (small number) from the mass number (big number). The answer is the number of neutrons.
Answer:
the motion of an object in a circular path , in a fixed orbit
Acceleration is defined as rate of change in velocity
So we can write its formula as

here we know that
= final velocity = 56 m/s
= initial velocity = 7.6 m/s
t = time interval to change the velocity = 3 s
now we will plug in all values in the above equation



so here roller coaster will accelerate at rate of 16 m/s^2 and hence correct answer is "option d"