force

• net (resultant) force

  net force acting on the object will make it accelerate in the direction the force is acting on
• F=ma

  force = mass * acceleration
• mass is constant for the particle concerned
• weight is the magnitude that is variable - this depends on the location.

  the weight of a person on earth is different to the weight of the same person on the moon
• w = mg

  weight = mass * gravity

  w = m * 9.81
• gravity on the moon - 1.6N