# Effect of air resistance of the period of a pendulum [duplicate]

Does air resistance increase or decrease the period of a simple pendulum?

## marked as duplicate by John Rennie newtonian-mechanics StackExchange.ready(function() { if (StackExchange.options.isMobile) return; $('.dupe-hammer-message-hover:not(.hover-bound)').each(function() { var$hover = $(this).addClass('hover-bound'),$msg = $hover.siblings('.dupe-hammer-message');$hover.hover( function() { $hover.showInfoMessage('', { messageElement:$msg.clone().show(), transient: false, position: { my: 'bottom left', at: 'top center', offsetTop: -7 }, dismissable: false, relativeToBody: true }); }, function() { StackExchange.helpers.removeMessages(); } ); }); }); Jun 15 at 9:32

• @eranreches For damped simple harmonic motion where the displacement is $x = Ae^{-\beta t}\cos \omega t$, the period is defined to be $2\pi/\omega$. This corresponds to a "common sense" idea of the period if the damping is small, and is consistent with the definition when $\beta = 0$. – alephzero Jun 15 at 9:08
Suppose the mass is at its maximum position, and moves to the central position in time $$t$$. If there is air resistance, the speed of movement of the mass will be less because the air resistance slows it down, and therefore $$t$$ will be larger.