PULLEYS
PULLEYS:
Pulley is a grooved wheel which rotates about a fixed axis by a
rope which passes round it. The axis is supported by a frame work or block.
Types
of pulleys
i)
Fixed pulleys
ii)
Movable pulleys
i)
Fixed Pulleys: These are used to alter
the direction of force. The pulley block is fixed and the rope which passes
round the wheel is attached to the weight at one end and the effort is applied
at the other.
ii)
Movable pulleys: These are used to gain
mechanical advantage when lifting heavy weights. Commonly used for lifting the
trunk for suspension exercises. The upper pulley is fixed to an overhead
support, to which one end of rope is attached. The rope is then wound round the
movable pulley, to which the weight is attached, and round the fixed pulley,
the effort being applied at the free end.
মন্তব্যসমূহ
একটি মন্তব্য পোস্ট করুন