Can someone explain what is referred by the cross sectional area of a solenoid? Would this be the same for an air solenoid vs a solenoid with a core vs a solenoid with a hollow core?

Experiment scenario 2: a biology student wants to conduct a study of how the amount of food affects the weight gain for mice. i have set up four cages with a mouse in each cage. fill in the boxes that would allow the biology student to complete the study correctly

Acaterpillar tries to climb straight up a wall a meter high, but for every 2 cm up it climbs, it slides down 1 cm. eventually, it reaches the top. when it reaches the top, it does not pull itself over so it will slide down 1 cm. what is the total displacement traveled?

Your friend increases her force on the desk by 30n . she doesn't change the direction of her push . what happens to the net force on the desk .will the desk accelerate