Atomic and Nuclear Physics Answers

Calculate the work done when an object of mass, 50kg is moved through a distance of 5m. (g=10m/s).

3. The half-life of radium-226 is 1600 years. If a sample of radium-226 has an original activity of 200 Bq, what will it’s activity be after 4800 years?

Sodium-24 has a half-life of 15 hours. If a sample of sodium-24 has an original activity of 500 Bq, what will its activity be after 60 hours?

Carbon-14 is a radioactive isotope of carbon which decays by β− emission. It has a half-life of 5700 years.
a i Explain the meaning of the term half-life.
(1 mark)
ii State the composition of a nucleus.

(2 marks)
b is produced when a nitrogen nucleus first absorbs a neutron in the atmosphere and then the resulting nuclide emits a proton.
i State the nuclear reaction equation for the production of from .

(2 marks)
ii Write down the stable nuclide into whichdecays by β− emission.

(2 marks)
c Living plants absorb carbon dioxide from the atmosphere, a small quantity of which contains. The β− activity, A0, from a living plant remains constant, but once the plant dies the activity decays according to the expression

where A is the activity at time t.
Calculate:
i the decay constant λ for

(2 marks)
ii the ratio .

A geological rock sample contains two radioactive isotopes, X and Y.
In the sample, there are N nuclei of X and 5N nuclei of Y. The half-life of isotope X is half of that of isotope Y. Y is not the product of X decaying nor is X the product of Y decaying.
The sample is stored for a time equal to two half-lives of isotope Y.
Determine the magnitude of the ratio

at the end of the storage period.


(3 marks)
b Polonium-210 is an alpha particle emitter with a decay constant of 5.80 × 10−8 s−1.
i Complete the decay equation below.


(2 marks)
ii Calculate the activity of 1.80 mg of polonium-210.


(3 marks)
iii How many nuclei of the polonium remain after 98 days?

An α particle having energy 10Mev collides with a nucleus of atomic mass 50 . Then distance of closest approach will be ?

(a) From the known masses of 15O and 15N, compute the difference in binding energy. (b) Assuming this difference to arise from the difference in Coulomb energy, compute the nuclear radius of 15O and 15N.

The half-life of cobalt-60 is 5.274 years. Calculate the activity of a sample of
cobalt-60 weighing 1 g in units of Curie (Ci).

The driver of a car suddenly applies the brakes hard for 2.6 s. As a result, an average force of 6200 N is exerted on the car to slow it. What is the impulse on the car?

It is possible to date radiometrically rocks and minerals that contain naturally radioactive elements. They are the basis for quantifying the timing and duration of geologic events and have produced an entire new subdiscipline of geology.What quantities can we measure?