2. joe runs up the stadium steps as an athletic drill. there are 50 steps and each one is 0.30 meters high and 0.50 meters deep. if joe has a mass of 95 kg and runs the steps in 30 seconds, how much work has he done and how much power has he dissipated? 3. a 950 kg car accelerates from 0 m/s to 25 m/s in 5.0 seconds. how much power does that require? 4. a pulley system is used to lift a 4500 n weight using a 900 n force. if the mass moves 1.0m while the pulley is pulled 6.0m, what is the efficiency of the machine? 5. a lever is used to lift a car engine that weighs 2200 n a distance of 1.0 meters. to accomplish this, a 550 n force is applied over a distance of 5.0 m. what is the efficiency of this machine?

To understand the behavior of the electric field at the surface of a conductor, and its relationship to surface charge on the conductor. a conductor is placed in an external electrostatic field. the external field is uniform before the conductor is placed within it. the conductor is completely isolated from any source of current or charge. part a: which of the following describes the electric field inside this conductor? it is in the same direction as the original external field.it is in the opposite direction from that of the original external field.it has a direction determined entirely by the charge on its surface.it is always zero. part b: the charge density inside the conductor is: 0non-zero; but uniformnon-zero; non-uniforminfinite part c: assume that at some point just outside the surface of the conductor, the electric field has magnitude e and is directed toward the surface of the conductor. what is the charge density η on the surface of the conductor at that point? express your answer in terms of e and ϵ0

Frank just graduated from eighth grade. assuming exactly four years from now he will graduate from high school how many seconds does he have until his high school graduation

Which statement best describes the direction of the buoyant force on any object? a. opposite the force of gravity b. in the same direction as the weight c. in the direction of motion of the object d. opposite the direction of motion of the object