Final answer:
Gravity Racers are propelled by centripetal force, which, in an amusement park ride where the floor drops, is the normal force from the barrel wall acting to keep the riders against the wall in their circular path. Experimental verification is key in physics, and car racing, including banking of tracks, is explained by these principles as well. For rocket sleds, rocket thrust is calculated to account for acceleration and opposing friction.
Step-by-step explanation:
Explanation of Forces in Gravity Racers
The force that propels Gravity Racers, such as the ride mentioned where riders are pinned against the wall of a rotating barrel, is due to centripetal force. In an inertial frame of reference, the real force that pins riders to the wall is not gravity but the normal force exerted by the wall of the barrel. This force acts towards the center of the circular path (centripetal) and is due to the riders' tendency to maintain a straight-line motion (inertia) while the barrel turns around them. This force is perpendicular to the surface they are pressed against. Additionally, friction between the riders and the wall helps to prevent them from sliding down.
In terms of action at a distance, the ultimate determinant of truth in physics is experimental verification. The concept of gravity as an action at a distance force was ultimately accepted because the predictions made by the theory of gravity were consistently confirmed by experimental observations and data.
For example, in car racing, the force that prevents a racecar from spinning out and keeps it on track through a turn, is also centripetal force, provided by the friction between the tires and the track. This is one example of how forces are analyzed and understood in physics to explain motion.
Gravitational Forces and Rocket Thrust
The gravitational force itself acts equally on all masses, but the apparent differences in falling objects near the Earth's surface can be attributed to air resistance rather than the gravitational pull itself. As for objects such as a rocket sled, the thrust must overcome both gravitational pull and friction to accelerate. The force required from each rocket to accelerate a sled can be calculated using Newton's second law, taking into account the mass, acceleration, and frictional forces involved.