4 A student says that an electromagnet is stronger when it has an iron core because the electric current flows through the iron as well as the wire. Is this correct? What would
you say to the student?

Rank the torques on the five doors shown in the figure above from least to greatest. note that the magnitude of all the forces is the same

An object thrown vertically upward from the surface of a celestial body at a velocity of 36 m/s reaches a height of sequalsminus0.9tsquaredplus36t meters in t seconds. a. determine the velocity v of the object after t seconds. b. when does the object reach its highest point? c. what is the height of the object at the highest point? d. when does the object strike the ground? e. with what velocity does the object strike the ground? f. on what intervals is the speed increasing?

What happens to light waves from a star as the star moves away from earth?