The force that holds two magnets together is the ONLY non-example of gravitational force. Except for the strong nuclear force, the weak nuclear force, the electrostatic force, the tidal force, the US Air Force, the force of destiny, the force of faith, the strength of one's convictions, and a few million other non-examples.
A non-example of force would be something that stay sill like a balloon in the air..... taste, smell, feel, texture, color, opinion, faith, hope, sincerity, honest, speed, momentum, altitude, volume, loudness, area, length, acidity, obesity, nationalism, current, resistance, viscosity, wavelength, flow, rate, frequency, albedo, diameter, age, temperature, acceleration, body mass index, salinity, specific, specific gravity, consciousness, intelligence, refraction index, mass, time, date rate, switching speed, libido, focal length, and latency are not force. And even there are many other things that also are not force, too.
A closed system is a system where exists energy interactions with surroundings, but not mass interactions. If we neglect any energy interactions from boundary work, heat, electricity, magnetism and nuclear phenomena and assume that process occurs at steady state and all effects from non-conservative forces can be neglected, then the equation of energy conservation is reduce to this form:
(1)
Where:
- Change in kinetic energy of the system, measured in joules.
- Change in gravitational potential energy of the system, measured in joules.
If we know that and , then we get the following equation:
(2)
Where and stands for initial and final states of each energy component.
Some work will be done on friction between wheels and road but it is negligible compared to work done on friction on breaks.
W = Ek = (m*v^2)/2 = 2000*22^2/2 = 1000*22^2 = 484KJ
Because car is not changing its potential energy, there is no work to be done on while changing it which means that all goes on changing kinetic energy (energy of motion)
When the football player is in the air at his maximum height the vertical component of velocity is zero, To obtain the horizontal velocity when the player catches the ball we need to apply the linear momentum conservation theorem:
we need to obtain the time taken to go down.
We have a horizontal displacement and the time taken to stop, so: