Half Life

All the earlier lessons are availble if you search the blog.

Radioactive Half Lives answers.

25s, ~27.5y, ~67d, ~70 min, ~62.5 hrs, ~162 days, ~ 1300y

E25 The Half Life of Radon Gas

a.They decay randomly

b The half life should be measured in variuos places on the graph to establish an accurate value. Approx 55s

c. The long half life of cobalt-60 would mean there was no perceptable change in activity during the short time of a laboratory experiment. 

E26 Ice Age Man 

a. Isotope - different nuclei of the same element, with different numbers of neutrons.

Unstable- incorrect balance of protons and neutrons, leading to emission of particle.

Beta (minus) particle - high energy electron emitted from an unsatble nucleus.

Half life - the time taken for half the nuclei of a given radioactive substance to decay.

b. 6 protons, 8 neutrons

c See main post on Radiocarbon dating

d 11 460 years ago

e it is too old

f The amount of carbon in the atmosphere has risen.

Questions on momentum

Momentum

Momentum = mass x velocity                                          kgms^-1 = kg x ms^-1

1.       A bowling ball has a mass of 10kg and a velocity of 15ms^-1. Calculate its momentum.                    150 kgms^-1

2.       A speed skater has a velocity of 15ms^-1 and a mass of 65 kg. Calculate her momentum.                 975 kgms^-1

3.       A bullet of mass 0.068 kg traveling horizontally at a speed of 150 ms^-1. Calculate its momentum. 10.2 kgms^-1

4.       The world record for bowling at cricket is 80 ms^-1. A cricket ball has a mass of 0.17kg. Calculate its momentum. 13.6 kgms^-1

5.       Calculate the momentum of a car of mass 1000kg travelling a velocity of 20ms^-1                                             2 x 10 ⁴ kgms^-1

6.       A jumbo jet has a mass of 30 000 kg. Calculate its momentum at cruising speed of 300ms^-1                          9 x 10 ⁶ kgms^-1

7.       A Eurostar train has a mass of 752t. (1t = 1000kg).  Calculate its momentum at top speed of 93 ms^-1 6.99x 10⁷kgms^-1

8.       An oil tanker has a mass of 100 x10⁶ kg and is travelling at 5ms^-1. Calculate its momentum.                         5 x 10⁸ kgms^-1

9.       The Earth has a mass of 5.9742 × 10²⁴ kg. Its orbital velocity is 29.8 kms^-1. Calculate its momentum. 1.73 x10²⁹ kgms^-1

10.    Jupiter has a mass of 1.8986×10²⁷ kg and an orbital velocity of 13.06 kms^-1. Calculate its momentum. 2.48 x10³¹ kgms^-1

11.    N₂ has an atomic mass of 4.65173 x 10^-26 kg. Calculate its momentum if it has a velocity 500 ms^-1 2.33 x 10^-23 kgms^-1

12.    The electron mass = 9.10938188 × 10^-31 kilograms. Calculate the momentum of an electron travelling at 0.1c (c = 3 x10⁸ ms^-1) 2.73 x10^-23 kgms^-1

Momentum

inverse square law

Help on Gas Laws questions

Gas Law equations

Gas pressure and absolute zero