help on 3 physics homework questions with a step by step

Overview

1. A jet pilot takes his aircraft in a vertical loop. If the jet is moving at a speed of 512.22 km/h at the lowest point of the loop, determine the minimum radius of the circle so that the centripetal acceleration at the lowest point does not exceed 6.0g’s.
2. Calculate the force of Earth’s gravity on a spacecraft 2.51 Earth radii above the Earth’s surface if its mass is 2505.99 kg.
3. How much work must be done to stop a 868.13 kg car traveling at 83.39- km/h?