Aspring-loaded piston-cylinder device is filled with 0.35 kg of water vapor that is initially at 4 mpa and 4000c. initially, the spring exerts no force against the piston. the spring constant in the spring-force relationship is k = 0.75 and the piston diameter is d = 20 cm. the water now undergoes a process until its volume is one-half of the original volume. calculate the final temperature and the specific enthalpy of the water.

A boiling pot of water (the water travels in a current throughout the pot), a hot air balloon (hot air rises, making the balloon rise) , and cup of a steaming, hot liquid (hot air rises, creating steam) are all situations where convection occurs. 
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Given Information:

Magnetic field = B = 13.5 T

Circumference of circular ring = c = 39 km

Required Information:

Maximum energy = E = ?

Maximum energy = 4×10⁻⁶ Joules

Explanation:

A charged particle experiences a magnetic force due to the magnetic field is given by

F = qvB

Where q is the magnitude of charge, v is the velocity and B is the magnetic field.

Since the charged particle is moving in a circular ring, the centripetal force acting on it is given by

F = mv²/r

Where m is the mass of charged particle and r is the radius of the circular ring.

qvB = mv²/r

qB = mv/r

but mv = p that is linear momentum of the charged particle

qB = p/r

p = qBr

The energy is given by

E = pc

Substitute p = qBr

E = qBrc

Where c is the speed of light c = 2.99×10⁸ m/s

First find the radius,

c = 2πr

r = c/2π

r = 39×10³/2π

r = 6207 m

So the energy of the charged particle is

E = qBrc

E = (1.60×10⁻¹⁹)(13.5)(6207)(2.99×10⁸)

E = 4×10⁻⁶ Joules