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.
The separation in time between the arrival of primary and secondary wave is called LAG TIME. The time difference between the arrival of primary wave and secondary wave in a seismogram is called lag time. The primary wave always travels faster than the secondary wave, thus the difference between the two can be obtained by estimating the difference between the arrival time of the two waves/.
According to Newton's second law of motion which states that "the rate of change in momentum of a body is directly proportional to the applied force F and acts in the direction of the force.
Mathematically;
F = ma
Since two forces acts on the cart i.e the moving force F and the frictional force Ff , we will take the sum of the forces.
∑F = ma where
m is the mass of the cart
a is its acceleration
∑F = F+(-ff )(since frictional force is an opposing force)
