(b) gives (c) gives gives Reflect: The SRBs have greater speed when they return to the ground than they had when released. After release they continue to travel upward. When they return to an altitude of 45 km on their way back down their speed is but they gain additional speed as they continue to fall to earth. 2.78. Set Up: Take to be the direction the car moves when speeding up. Use the acceleration and stopping data to find a in each case. Design the on-ramp for the less powerful car and the off-ramp for the car with bald tires. Solve: on-ramp (speeding up): and gives Then and in gives This is the required length of the on-ramp. off-ramp (slowing down): and gives Then and in gives This is the required length of the off-ramp. 2.79. Set Up: The time interval of 35 years is Solve: The minus sign means that is directed opposite to the speed of growth is decreasing in time. 2.80. Set Up: Let be to the right. (a) is constant so is constant and positive. (b) increases so is positive and increasing. (c)
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Trigraph, Orders of magnitude, required length, vx increases