Uma prancha homogênea de 10 m de comprimento e peso 600 N está apoiada por dois rolos conforme a figura. O menino se desloca lentamente de tal forma que o atrito do rolo, com a prancha e o solo, seja capaz de impedir o deslocamento horizontal da prancha. A que distância máxima x da extremidade direita da prancha deve ser posicionado o rolo B para que o menino de peso 400 N, partindo de A, possa caminhar até a extremidade direita sem a mesma girar?

Aspecial electronic sensor is embedded in the seat of a car that takes riders around a circular loop-the-loop ride at an amusement park. the sensor measures the magnitude of the normal force that the seat exerts on a rider. the loop-the-loop ride is in the vertical plane and its radius is 23 m. sitting on the seat before the ride starts, a rider is level and stationary, and the electronic sensor reads 740 n. at the top of the loop, the rider is upside down and moving, and the sensor reads 370 n. what is the speed of the rider at the top of the loop?

How does convection affect our atmosphere? our layers of earth? our oceans?

Acar traveling at 22 m/s starts to decelerate steadily. it comes to a complete stop in 15 seconds. what is it’s acceleration?