A lens has a focal length of 0.4m What is it's power?

What tightening torque should be used for a hexagonal head screw (not split-bolt) on a 250 kcmil conductor?

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?

Distinguish between linear momentum and angular momentum