The speed of the wind is changing according to the function V (t) = -t/2 + 30, where t = time in minutes after 6:00 p. m. and V(t) = wind speed in miles per hour (mph). Which statement best describes the meaning of the equation V(20) – V(10) = -5?

A) In a period of 5 minutes, the wind speed increased from 10 mph to 20 mph.

B) The wind speed decreased by 5 mph between 6:10 p. m. and 6:20 p. m.

C) The wind speed increased by 5 mph between 6:10 p. m. and 6.20 p. m.

D) In a period of 5 minutes, the wind speed decreased from 20 mph to 10 mph.

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?