Mr. smith challenged his students to create an electromagnet that will pick up more paper clips than anyone else in the class. timmy is very excited and begins to collect all of the necessary materials. he finds a d-cell battery, an iron nail, and a large roll of copper wire. what could timmy do, using just these materials, to increase the strength of his electromagnet to pick up the maximum amount of paper clips?

In which situation has the independent variable for the experiment been changed? check all that apply. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of ph on duckweed growth to testing the effect of light levels on duckweed growth changed from testing the effect of acid ph on duckweed growth to testing the effect of basic ph on duckweed growth

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Humidity is to blame for that muggy, steamy feeling you experience on some hot summer days. what gas in the atmosphere causes humidity? a) oxygen b) hydrogen c) nitrogen d) water vapor