Assignment:
In the amusement park ride known as Magic Mountain Superman, powerful magnets accelerate a car and its riders from rest to 39 m/s (around 90 mi/h) in a time of 5.9 s. The mass of the car and riders is 5700 kg. Find the average net force exerted on the car and riders by the magnets.
A person with a blackbelt in karate has a fist that has a mass of 0.54 kg. Starting from rest, this fist attains a velocity of 8.3 m/s in 0.18 s. What is the magnitude of the average net force applied to the fist to achieve this level of performance?
A rock of mass 44 kg accidentally breaks loose from the edge of a cliff and falls straight down. The magnitude of the air resistance that opposes its downward motion is 260 N. What is the magnitude of the acceleration of the rock?
A student presses a book between his hands, as the drawing indicates. The forces that he exerts on the front and back covers of the book are perpendicular to the book and are horizontal. The book weighs 33 N. The coefficient of static friction between his hands and the book is 0.33. To keep the book from falling, what is the magnitude of the minimum pressing force that each hand must exert?
The helicopter in the drawing is moving horizontally to the right at a constant velocity. The weight of the helicopter is W= 56100 N. The lift force generated by the rotating blade makes an angle of 21.0° with respect to the vertical.
(a) What is the magnitude of the lift force?
(b) Determine the magnitude of the air resistance that opposes the motion.