In 1903 Marie Curie won the Nobel prize for which of the following? 1. She realized that pitchblende was more radioactive than uranium
2. She developed ways to separate radium from other materials
3. She and her husband discovered two new chemical elements, polonium, and radium
4. She helped discover that radioactive materials are life-threatening

The motor m applies a time-varying force of f (200 t) n, where t is in seconds. box b with mass 200 kg starts from rest, and the coefficients of kinetic and static friction are 0.2 and us 0.3 the acceleration due to gravity is g 9.8 m/s2 b 300 a) find the time ' when the box starts to move. b) calculate the speed of the crate at 3 s c) calculate the power delivered by the motor at t 3 s

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?

Greg drew a diagram to compare two of the fundamental forces. which labels belong in the areas marked x, y and z? gravitational force electromagnetic force x. attractive y repulsive z: infinite range x: infinite range y attractive z. repulsive x. always attractive y: infinite range z: attractive or repulsive x. attractive or repulsive y infinite range z: always attractive