We can solve the problem by using the first law of thermodynamics, which states that:
where
is the change in internal energy of the system
Q is the heat absorbed by the system
W is the work done by the system
In our problem, the heat absorbed by the system is Q=+194 kJ, while the work done is W=-120 kJ, where the negative sign means the work is done by the surroundings on the system. Therefore, the variation of internal energy is
Answer:
Circle
Explanation:
When a charged particle is in motion in a region with magnetic field, the particle experiences a force whose magnitude is given by
where
q is the charge
v is the velocity of the particle
B is the strength of the magnetic field
is the angle between the directions of v and B
In this problem, the velocity of the particle is perpendicular to the magnetic field, so
and the formula reduces to
Also, the direction of this force is perpendicular to the direction of motion of the particle. This means that as the charge moves in the region of the magnetic field, the force acting on it acts as a centripetal force: therefore, the particle will start moving by unifom circular motion, with constant speed (because the magnetic force does no work on the particle, since it is perpendicular to the direction of motion).
So, the path of the particle will be a circle.
Centripetal acceleration points from the object toward the center of the circular path it's traveling.
Jane's mechanical energy at any time is
where
is the potential energy, while
is the kinetic energy.
Initially, Jane is on the ground, so the altitude is h=0 and the potential energy is zero: U=0. She's running with speed v, so she has kinetic energy only:
Then she grabs the vine, and when she reaches the maximum height h, her speed is zero: v=0, and so the kinetic energy becomes zero: K=0. So now her mechanical energy is just potential energy:
But E must be conserved, so the initial kinetic energy must be equal to the final potential energy:
from which we can find h, the maximum height Jane can reach:
