It are type of lever machine
Explanation:The wheel and axle is a machine consisting of a wheel attached to a smaller axle so that these two parts rotate together in which a force is transferred from one to the other. A hinge or bearing supports the axle, allowing rotation. It can amplify force; a small force applied to the periphery of the large wheel can move a larger load attached to the axle.The wheel and axle can be viewed as a version of the lever, with a drive force applied tangentially to the perimeter of the wheel and a load force applied to the axle, respectively, that are balanced around the hinge which is the fulcrum. The mechanical advantage of the wheel and axle is the ratio of the distances from the fulcrum to the applied loads, or what is the same thing the ratio of the diameter of the wheel and axle. A major application is in wheeled vehicles, in which the wheel and axle are used to reduce friction of the moving vehicle with the ground. Other examples of devices which use the wheel and axle are capstans, belt drives and gears.
keep away from concrete floors or walls. lightning can travel through any metal wires or bars in concrete walls or flooring. avoid water during a thunderstorm. lightning can travel through plumbing.
expression for kinetic energy :
suppose a force ‘f’ acting on a body of mass ‘m’ in state of rest changes its velocity to ‘v’ and body covers ‘s’ distance in the direction of force.
then, the work done by the force is given by
w = f . s
= ma . s (1) [ f = ma ]
now, using equation of motion, we have
v2 = u2 + 2as
or, v2 = 0 + 2as
as = v2/2
so, by equation (1) , we get
w = m .v2/2
so , by definition of kinetic energy of the body,
k.e. = w = 1/2 mv2