Two positively charged objects are located so they are 0.20 m apart. if the objects are separated until their centres are 0.40 m apart, by what factor will the electrostatic force between them change?

Aboxcar traveling at 12 m/s approaches a string of 5 identical boxcars sitting stationary on the track. the moving boxcar collides and links with the stationary cars and they all move off together along the track. what is the final speed of the cars immediately after the collision? (you may take the mass of each boxcar to be 18,537 kg.)

The coefficient of friction is a number that represents the resistance to sliding between two in contact with one another.

What occurs during a combustion reaction