The half-life of radium-226 is 1600 years. How many grams of a 7 g sample will remain after 3200 years?
SHOWALL STEPS TO SOLVE THE PROBLEM

1600 years half life

3200/1600 is 2 half lifes

first half life takes the sample to 1/2 it's original amount and the second takes it to 1/4 of it's original amount

so 1/4*7gm is 1.75gm

Explanation:

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

490 n

f=125n a=2.5m/s2