External force Definition and 56 Threads

I’m an electrical engineer. When explaining gravity in GR terms to my peers, and I get to the part about there being no net force acting upon an object that’s “free falling” in curved spacetime, I have difficulty countering the argument: “Yeah, you can’t measure a net force because gravity is...

Hi, I am new poster on this forum. Apologies if you have already answered a similar problem before. let me get to the point straightaway. Now consider one example: Take a shopping cart and sit in it. Now jerk your body in any manner you require. The goal is to create a net motion forward...

Hello, First time post here, so if I violate some rules of protocol etc. please forgive and let me know! Anyway, I've been asking profs and other physicists this question, and the more-knowledgable the person I ask, the more complex the answer sounds! Two basic setups: (1) two masses...

My wife is taking a Physics class and is having some trouble. I've never taken physics but I've tried to help, with no luck. Homework Statement What net external force is required to accelerate a 1500kg car from rest to 100km/h in 10 seconds? Homework Equations She believes that the right...

We know intuitively that a gyroscope in zero gravity (or free fall) can spin almost indefinitely with either a zero or 90 degree precession angle (i.e., spinning perfectly along its axis or along its "side," respectively). Why shouldn't it be able to spin at intermediate states, such as with a...

Mass of 2.6kg lies on a frictionless table, pulled by another mass of 4.1kg under the influence of gravity (mass 4.1kg is hanging off the edge of the table). The acceleration due to gravity is 9.8m/s^2. What is the magnitude of the net external force (gravitational) acting on the two masses...