Acceleration happens when a force acts on an object with mass. The greater the mass (from the object) the greater the force has to be in order to move the object.
Example: Imagine pushing a wagon, (that doesn't take much force!!!!) it's easy right? Now imagine pushing a four-wheeler, (now that's hard) you need exert more force in order for the four-wheeler to accelerate. Does it make sense now, the more the mass the more force you need in order for the object to move.
Example: Imagine pushing a wagon, (that doesn't take much force!!!!) it's easy right? Now imagine pushing a four-wheeler, (now that's hard) you need exert more force in order for the four-wheeler to accelerate. Does it make sense now, the more the mass the more force you need in order for the object to move.