3. In the amusement park ride known as Magic Mountain Superman, powerful magnets accelerate a car and its riders from rest to 45 m/s (about 100 mi/h) in a time of 7.0 s. The mass of the car and riders is 5.5 X 103 kg. Find the average net force exerted on the car and riders by the magnets.
19. On earth, two parts of a space probe weigh 11 000 N and 3400 N. These parts are separated by a center-to-center distance of 12 m and may be treated as uniform spherical objects. Find the magnitude of the gravitational force that each part exerts on the other out in space, far from any other objects.
25. The mass of a robot is 5450 kg. This robot weighs 3620 N more on planet A than is does on planet B. Both planets have the same radius of 1.33 X 107 m. What is the difference MA - MB in the masses of these planets?
This post provides step by step calculations for net force, magnitude of gravitational force, and masses of planets.