Tracy stands on a skateboard and tosses her backpack to her friend who is standing in front of her. which best describes the acceleration tracy experiences? it is less than the acceleration of the backpack because she has a greater mass. it is greater than the acceleration of the backpack because she has a greater mass. it is less than the acceleration of the backpack because she uses a smaller force. it is greater than the acceleration of the backpack because she uses a larger force.