Bluetooth is a technology that allows wireless devices to communicate data and information to each other. for example, a wireless pair of headphones can play music from a smart phone without a physical connection. however, the technology must be low energy enough not to cause damage to the people using the device. additionally, the wavelengths used in bluetooth technologies should not be visible. the waves associated with bluetooth technology are most similar to which wave type below?
b) red light
c) radio waves
d) uv radiation
at thermal equilibrium, the heat given by the hotter mass of water must be equal to the heat absorbed by the colder water (because energy cannot be destroyed nor created). in formula:
is the mass of the hot water
ch is the specific heat of the hot water
is the variation in temperature of the hot water
is the mass of the cold water
cc is the specific heat of the cold water
is the variation in temperature of the c water
we notice that:
since the two masses are equal, and
because the substance is the same (water)
so, the above equation just simplifies as
which can be rewritten as:
where t_f is the temperature of both masses of water at equilibrium. by solving the equation, we find
explanation : when the lift falls, then the gravitational energy changed into the kinetic energy. gravitational potential is associated with the mass of the lift and its position. when lift starts from rest , the mechanical energy of the lift change in the form of potential energy.
when the lift down than the potential energy lost and kinetic energy is gained. lift loses height and gains speed.
the work is performed by the lift, when lift covers the distance against the gravitational force.