function getmechanics()
{
if(document.getElementById){document.getElementById('mechanics-menu').style.display='block';document.getElementById('electricity_electronics-menu').style.display='none';document.getElementById('waves_optics-menu').style.display='none';document.getElementById('radioactivity-menu').style.display='none';document.getElementById('matter-menu').style.display='none';document.getElementById('space-menu').style.display='none';document.getElementById('miscellaneous-menu').style.display='none';document.getElementById('mechanicstab').className='menu-selected';document.getElementById('electricity_electronicstab').className='menu-unselected';document.getElementById('waves_opticstab').className='menu-unselected';document.getElementById('radioactivitytab').className='menu-unselected';document.getElementById('propertiesofmattertab').className='menu-unselected';document.getElementById('spacetab').className='menu-unselected';document.getElementById('miscellaneoustab').className='menu-unselected'}
}
function getelectricity_electronics()
{
if(document.getElementById){document.getElementById('mechanics-menu').style.display='none';document.getElementById('electricity_electronics-menu').style.display='block';document.getElementById('waves_optics-menu').style.display='none';document.getElementById('radioactivity-menu').style.display='none';document.getElementById('matter-menu').style.display='none';document.getElementById('space-menu').style.display='none';document.getElementById('miscellaneous-menu').style.display='none';document.getElementById('mechanicstab').className='menu-unselected';document.getElementById('electricity_electronicstab').className='menu-selected';document.getElementById('waves_opticstab').className='menu-unselected';document.getElementById('radioactivitytab').className='menu-unselected';document.getElementById('propertiesofmattertab').className='menu-unselected';document.getElementById('spacetab').className='menu-unselected';document.getElementById('miscellaneoustab').className='menu-unselected'}
}
function getwaves_optics()
{
if(document.getElementById){document.getElementById('mechanics-menu').style.display='none';document.getElementById('electricity_electronics-menu').style.display='none';document.getElementById('waves_optics-menu').style.display='block';document.getElementById('radioactivity-menu').style.display='none';document.getElementById('matter-menu').style.display='none';document.getElementById('space-menu').style.display='none';document.getElementById('miscellaneous-menu').style.display='none';document.getElementById('mechanicstab').className='menu-unselected';document.getElementById('electricity_electronicstab').className='menu-unselected';document.getElementById('waves_opticstab').className='menu-selected';document.getElementById('radioactivitytab').className='menu-unselected';document.getElementById('propertiesofmattertab').className='menu-unselected';document.getElementById('spacetab').className='menu-unselected';document.getElementById('miscellaneoustab').className='menu-unselected'}
}
function getradioactivity()
{
if(document.getElementById){document.getElementById('mechanics-menu').style.display='none';document.getElementById('electricity_electronics-menu').style.display='none';document.getElementById('waves_optics-menu').style.display='none';document.getElementById('radioactivity-menu').style.display='block';document.getElementById('matter-menu').style.display='none';document.getElementById('space-menu').style.display='none';document.getElementById('miscellaneous-menu').style.display='none';document.getElementById('mechanicstab').className='menu-unselected';document.getElementById('electricity_electronicstab').className='menu-unselected';document.getElementById('waves_opticstab').className='menu-unselected';document.getElementById('radioactivitytab').className='menu-selected';document.getElementById('propertiesofmattertab').className='menu-unselected';document.getElementById('spacetab').className='menu-unselected';document.getElementById('miscellaneoustab').className='menu-unselected'}
}
function getmatter()
{
if(document.getElementById){document.getElementById('mechanics-menu').style.display='none';document.getElementById('electricity_electronics-menu').style.display='none';document.getElementById('waves_optics-menu').style.display='none';document.getElementById('radioactivity-menu').style.display='none';document.getElementById('matter-menu').style.display='block';document.getElementById('space-menu').style.display='none';document.getElementById('miscellaneous-menu').style.display='none';document.getElementById('mechanicstab').className='menu-unselected';document.getElementById('electricity_electronicstab').className='menu-unselected';document.getElementById('waves_opticstab').className='menu-unselected';document.getElementById('radioactivitytab').className='menu-unselected';document.getElementById('propertiesofmattertab').className='menu-selected';document.getElementById('spacetab').className='menu-unselected';document.getElementById('miscellaneoustab').className='menu-unselected'}
}
function getspace()
{
if(document.getElementById){document.getElementById('mechanics-menu').style.display='none';document.getElementById('electricity_electronics-menu').style.display='none';document.getElementById('waves_optics-menu').style.display='none';document.getElementById('radioactivity-menu').style.display='none';document.getElementById('matter-menu').style.display='none';document.getElementById('space-menu').style.display='block';document.getElementById('miscellaneous-menu').style.display='none';document.getElementById('mechanicstab').className='menu-unselected';document.getElementById('electricity_electronicstab').className='menu-unselected';document.getElementById('waves_opticstab').className='menu-unselected';document.getElementById('radioactivitytab').className='menu-unselected';document.getElementById('propertiesofmattertab').className='menu-unselected';document.getElementById('spacetab').className='menu-selected';document.getElementById('miscellaneoustab').className='menu-unselected'}
}
function getmiscellaneous()
{
if(document.getElementById){document.getElementById('mechanics-menu').style.display='none';document.getElementById('electricity_electronics-menu').style.display='none';document.getElementById('waves_optics-menu').style.display='none';document.getElementById('radioactivity-menu').style.display='none';document.getElementById('matter-menu').style.display='none';document.getElementById('space-menu').style.display='none';document.getElementById('miscellaneous-menu').style.display='block';document.getElementById('mechanicstab').className='menu-unselected';document.getElementById('electricity_electronicstab').className='menu-unselected';document.getElementById('waves_opticstab').className='menu-unselected';document.getElementById('radioactivitytab').className='menu-unselected';document.getElementById('propertiesofmattertab').className='menu-unselected';document.getElementById('spacetab').className='menu-unselected';document.getElementById('miscellaneoustab').className='menu-selected'}
}