Evaporation of sweat cools the skin because
1 answer:
Answer: c. the molecules with the highest energy evaporate first, lowering the temperature of the sample
Explanation:
The process by which liquid starts to change into vapor phase at any temperature is known as evaporation.
During evaporation , the molecules which possess higher energies escape from the upper layer into vapor phase. the molecules which escape draw energy from surroundings and thus decrease the energy of the surroundings and hence lead to decrease in temperature.
As temperature of the system is directly proportional to the energy of the system , thus decrease in energy leads to decrease in temperature.
K.E. = Kinetic energy
T = temperature
R= gas constant
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Answer:
Explanation:
Given that
Mass of rifle = M
Initial velocity ,u= 0
Mass of bullet = m
velocity of bullet = v
Lets take final speed of the rifle is V
There is no any external force ,that is why linear momentum of the system will be conserve.
Initial linear momentum = Final linear momentum
M x 0 + m x 0 = M x V + m v
0 = M x V + m v
Negative sign indicates that ,the recoil velocity will be opposite to the direction of bullet velocity.
The direction of the force changes, so, the ion will now rotate in the opposite direction
Explanation:
The force experienced by a moving charge in a magnetic field is (assuming the motion of the charge is perpendicular to the magnetic field)
(1)
where
q is the charge
v is the velocity of the particle
B is the strength of the magnetic field
Moreover, the direction of the force is perpendicular to the motion of the particle: this means that the particle moves in a circular motion under the action of this magnetic force.
Equating this force to the centripetal force,
Where m is the mass of the particle. So we find that the radius of the orbit (r) is
(2)
In this problem, an ion with initial charge +1 picks 2 electrons and its charge becomes -1.
- From eq.(1), we notice that since the sign of q changes, the direction of the force changes as well: so, the ion will now rotate in the opposite direction
- Moreover, from eq.(2) we notice that as the absolute value of q does not change, then the radius of the orbit does not change.