Planets are not uniform inside. Normally, they are densest at the center and have decreasing density outwards toward the surface. Model a spherically symmetric planet, with the same radius as Earth, as having a density that decreases linearly with distance from the surface. Let the density be 15000 kg/m3 at the center and 2000 kg/m3 at the surface. What is the acceleration due to gravity at the surface of this planet

The cheetah is considered the fastest running animal in the world. cheetahs can accelerate to a speed of 20.1 m/s in 2.50 s and can continue to accelerate to reach a top speed of 28.1 m/s. assume the acceleration is constant until the top speed is reached and is zero thereafter.1) starting from a crouched position, how long does it take a cheetah to reach its top speed? (express your answer to three significant figures.) s2) how far does it travel in that time? (express your answer to three significant figures.) m3) if a cheetah sees a rabbit 120 m away, how long will it take to reach the rabbit, assuming the rabbit does not move? (express your answer to three significant figures.)