Physics 2019 paper

% increase = increase / original number x 100

Example - 

( 10 000 - 3200 ) / 3200 x 100 = 212.6% 

Coal vs Gas

eviromental advantage to gas-fired power station compared to coal-fired power station :

-   no sulfur dioxide released

-   doesnt cause acid rain

-   no particulates released

-   doesnt cause global dimming

-   less carbon dioxide released

-   less global warming

-   no solid waste

-   gas mining is less destructive than coal mining

-   x-rays

-   radiotherapy

-   nuclear weapons

-   nuclear distaster ( e.g. chernobyl )

-   CT scans

-   nuclear fallout

The main nuclear fuels are - 

-   uranium

-   plutonium

step 1 -   neutron absorbed by a iranium nucleus

step 2 -   nucleus splits into two parts

step 3 -   nuetrons released and gamma rays emitted

How does the process of nuclear fission lead to release of energy?

lighter nuclei join to form heavier nuclei

some of the mass of the nuclei is converted to energy

Advantages of Radioactive waste having a shorter half-life :

-   activity decreases quickly

-   risk of harm decreases quickly

Energy = mass x specific heat capacity x change in temperature

Mass = energy / specific heat capacity x change in temperature

Specific heat capacity = energy / mass x change in temperature

Change in temperature = energy / mass x specific heat capacity

mean = add up all values then divide by number of values

Example :

3 , 5 , X , 9   mean = 6

3 + 5 + X + 9 / 4  = 6   [ multiply both sides by 4 ]

3 + 5 + X + 9 = 24  [ add up known values ]

17 + X = 24  [ subract 17 from both sides ]

X = 7