What is an item in which magnetic domains can be aligned and a magnetic field induced for a short period of time
2 answers:
You might be interested in
Answer:
The rotational kinetic energy takes 0.430 seconds to become half its initial value.
Explanation:
By the Principle of Energy Conservation and the Work-Energy Theorem we know that flywheel slow down due to the action of non-conservative forces (i.e. friction), the energy losses are equal to the change in the rotational kinetic energy. That is:
(1)
Where:
- Energy losses, measured in joules.
,
- Initial and final rotational kinetic energies, measured in joules.
By definition of rotational kinetic energy, we expand the equation above:
(2)
Where:
- Moment of inertia of the flywheel, measured in kilograms per square meter.
,
- Initial and final angular speed, measured in radians per second.
If we know that ,
and
, then the initial angular speed is:
(3)
(4)
Under the assumption that flywheel is decelerating uniformly, we get that the time taken for the flywheel to slowdown is:
(5)
If we know that ,
and
, then the time needed is:
The rotational kinetic energy takes 0.430 seconds to become half its initial value.
Answer:
0
7500J
7500J
Explanation:
Given parameters:
Mass of car = 600kg
Velocity = 5m/s
Unknown:
Original kinetic energy = ?
Final kinetic energy = ?
Work used = ?
Solution:
The kinetic energy of a body is the energy due to the motion of a body.
It can be solve mathematically using expression below;
K.E = m v²
where m is mass
v is velocity
original kinetic energy;
The car started at rest and v = 0, therefore K.E = 0
Final kinetic energy;
K.E = x 600 x 5² = 7500J
Work done:
Work done = Final K.E - Initial K.E = 7500 - 0 = 7500J