A tourist bus is carrying passengers from the bottom of a hill to the top. The people, the bus, and the luggage can be analyzed
2 answers:
Answer:
The total amount of energy in the system decreases as the bus travels. This situation happens because some of the kinetic energy changes to thermal energy because of friction between the tires and the road.
Explanation:
In an isolated system (= no external forces acting on it), the mechanical energy of the system remains constant:
where U is the potential energy and K is the kinetic energy.
In this case, however, the system is not isolated. In fact, there is an external force acting on the bus: the force of friction. The force of friction acts against the motion of the bus, therefore the bus loses part of its energy, and its total energy decreases. This energy is converted into thermal energy (motion of the molecules of the surface of the road and of the wheel)
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a) The angular velocity of the electron is
b) The number of revolutions per second is rev/s
c) The centripetal acceleration of the electron is
Explanation:
a)
This is a problem of uniform circular motion: in fact, the electron orbits around the proton in a uniform circular motion.
The angular velocity of an object in uniform circular motion is given by
where
v is the linear speed
r is the radius of the trajectory
For the electron orbiting around the proton, we have
Therefore, the angular velocity is
b)
The period of revolution of the electron is given by
where
is the angular velocity
Substituting,
The period is the time the electron takes to make one complete orbit around the proton; therefore, the number of revolutions of the electrons in one second is:
rev/s
c)
The centripetal acceleration of an object in circular motion is
where
v is the linear speed
r is the radius of the circle
For the electron, we have
Therefore, the centripetal acceleration is
Learn more about circular motion:
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