A small car with mass 0.800 kg travels at constant speed on the inside of a track that is a vertical circle with radius 5.00 m (Fig. E5.45). If the normal force exerted by the track on the car when it is at the top of the track (point B) is 6.00 N, what is the normal force on the car when it is at the bottom of the track (point A)?

Video transcript

Welcome back everybody, we have a skateboarder that is going back in forth on this half pipe right here. And we are told a couple different things about the skateboarder, we are told that his mass is 55 kg and we are also told that the radius of curvature of this ramp is five meters. Were also told that at the bottom here of the ramp he reaches a max speed of eight m per second. And we are tasked with finding what the force is of the ramp acting on the skater. So I'm just gonna call that force up. Well the skaters not floating away and the ramp is not collapsing below him. So we know that force up is going to be equal to the magnitude of the summation of all forces acting downward or from the skater onto the ramp. What are those forces? Well, we are going to have the force due to gravity which is just going to be the master skater times gravitational acceleration, since he is also following centripetal motion here, we know that the skater is going to be pushing down on the ramp with this force right here of mass, times his velocity squared times the radius of curvature. Now, if we sum these two forces together and then take the absolute value, we are going to find the force of our upward force. Let's go ahead and plug in those values here. Force of the upward force is going to be the absolute value of well, we have our mass, which is 55 times our acceleration due to gravity, which is 9.8 plus our mass once again times our speed squared all over our radius, which when you plug this into your calculator, you get that. The upward force Is 1, Newtons, which corresponds to answer choice. C. Thank you guys so much for watching. Hope this video helped. We will see you all in the next one.