Ravi uses a pulley system to lift a 79 N weight by 9.0m. If he pulls his end of the rope a distance of 3.0m, then which of the following would be the force he uses? (Assume the pulley is 100% efficient). A. 24N
B. 79N
C. 710N
D. 240N
E. 8.1N

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10^−2 cm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cm . the potential difference between the anode and cathode is 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.

What is the force that opposes motion and works against the downward pull? a) friction b) gravity c) weight d) acceleration

Select all the correct answers. which three statements about electromagnetic radiation are true?