The laws of physics which apply when you are at rest on the earth also apply when you are in any reference frame which is moving at a constant velocity with respect to the earth. For example, you can toss and catch a ball in a moving bus if the motion is in a straight line at constant speed.
Newton's second law shows that there is a direct relation ship between force and acceleration . the grater force that is applied on a object of given mass the more the accelerate. for example doubling the force in the object doubles it's acceleration.
