All atoms of the element potassium have 19 protons. one of the most stable types of potassium atoms has the mass number 39. how many neutrons make up one of these potassium atoms?
a. 19
b. 29
c. 38
d. 58

N = 20

Explanation:

As we know that mass number is the sum of number of protons and number of neutrons present in the atom

So we will have

mass number

number of protons in the given atom (Z) = 19

so we will have

A = Z + N

39 = 19 + N

N = 20

the area between the graph and the t axis

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s