You are testing a new roller coaster ride in which a car of mass mm moves around a vertical circle of radius RR. In one test, the car starts at the bottom of the circle (point A) with initial kinetic energy KiKi. When the car reaches the top of the circle (point B), its kinetic energy is Ki/4Ki/4, and its gravitational potential energy has increased by Ki/2Ki/2. What was the speed of the car at point A, in terms of gg and RR?

An astronaut floating in space is trying to use her jetpack to get back to her space station, but she is being pulled away by a nearby planet, as shown in the image below. her jetpack provides a constant thrust of 310 n. if she angles her jetpack in such a way that it cancels out the vertical force due to the planet's gravity, what is her net horizontal force? thaud 487 o a. 54.8 n toward the space station o b. 212.9 n toward the space station o c. 185.2 n toward the space station o d 956 n toward the space station