Iput 45 use what you have learned from this chapter to make a model boat out of a 10-cm square piece of foil. test your model boat in a tank of water to see how many pennies it can support before sinking. compare the performance of your boat with those of your classmates. suggest several design improvements based on your results. respond to at least one other students posting giving suggestions on how the model of their boat or yours could be improved to increase buoyancy.

Aspacecraft can attain a stable orbit 300 kilometers above earth if it reaches a velocity of 7.7 kilometers per second. the formula for a rocket's maximum velocity v in kilometers per second is vequalsminus0.0098tplusc ln upper r, where t is the firing time in seconds, c is the velocity of the exhaust in kilometers per second, and r is the ratio of the mass of the rocket filled with fuel to the mass of the rocket without fuel. find the velocity of a spacecraft whose booster rocket has a mass ratio of 20, an exhaust velocity of 2.1 km/s, and a firing time of 15 s. can the spacecraft achieve a stable orbit 300 km above earth?