A student tries to push a refrigerator-sized box of textbooks safely across the classroom. The box does not move. He asks for help from other students.

The box starts to move when the number of students shown in the image is pushing together.

Based on this information, what conclusion can be drawn?

The box has a mass greater than the combined mass of the first two students pushing.

The forces acting on the box became unbalanced when the third student started pushing.

The only force acting on the box is the push applied by the students.

When the third student started to push, the box’s mass decreased

The forces acting on the box became unbalanced when the third student started pushing.

Explanation:

The horizontal forces, friction and applied, were balanced until more force was applied than friction. Mass can't increase or decrease.

The forces acting on the box became unbalanced when the third student started pushing.

Explanation:

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .

it will increase due to the time span