Driving down the road at a speed of 26.1 m/s, you suddenly notice a fallen tree blocking the road a distance of 86.7 m ahead of you. You step on the brake pedal and decelerate at a constant rate. What must the magnitude of your acceleration be so that you will come to a stop 8.0 m in front of the tree? 1 4.33 m/s^2 2 3.93 m/s^2 3 3.60 m/s^2 4 8.66 m/s^2

A car starts from rest, then accelerates at a constant rate over a distance of 89 m. It then immediately decelerates at a constant rate over a distance of 152 m. The entire trip lasts a total duration of 27.2 s. What were the magnitudes of the car s accelerations for the speedup and slowdown stages respectively? 1.    1.76 m/s^2, then 1.03 m/s^2 2.    3.27 m/s^2, then 5.59 m/s^2 3.    0.65 m/s^2, then 0.65 m/s^2 4.    5.59 m/s^2, then 3.27 m/s^2

A car accelerates in the +x direction from rest with a constant acceleration of a1 = 1.92 m/s2 for t1 = 20 s. At that point the driver notices a tree limb that has fallen on the road and brakes hard with a constant acceleration of a2 = -9.3 m/s2. If the limb is on the road at a distance of 550 meters from where the car begins its initial acceleration, will the car hit the limb?

The position of a particle moving along the x axis is given by x(t) = 7t² - 1.7t³, where x is in meters and t in seconds. What is the position of the particle when it achieves its maximum speed in the positive x direction?

A rocket-powered sled moves along a track, eventually reaching a top speed of 219 m/s to the east. It then begins to slow down, reaching a complete stop after slowing down for 4.98 s. What was the sled s average acceleration and velocity during the slowdown phase?     44.0 m/s^2 east, not enough information     109.5 m/s^2 west, 109.5 m/s west     44.0 m/s^2 west, not enough information     0 m/s^2 0, 109.5 m/s east

Two soccer players start from rest, 39 m apart. They run directly toward each other, both players accelerating. The first player's acceleration has a magnitude of 0.48 m/s². The second player's acceleration has a magnitude of 0.49 m/s². (a) How much time passes before the players collide? (b) At the instant they collide, how far has the first player run? (a) Number M. (b) Number i Units Units ✪

Mature salmon swim upstream, returning to spawn at their birthplace. During the arduous trip they leap vertically upward over waterfalls as high as 3.31 m. With what minimum speed (in m/s) must a salmon launch itself into the air to clear a 3.31-m waterfall? in m/s

A hot-air balloon is drifting in level flight due east at 3.0 m/s due to a light wind. The pilot suddenly notices that the balloon must gain 20 m of altitude in order to clear the top of a hill 130 m to the east. How much time does the pilot have to make the altitude change without crashing into the hill? What minimum, constant, upward acceleration is needed in order to clear the hill?

From the top of a cliff, a person throws a stone straight downward. The initial speed of the stone just after leaving the person's hand is 9.7 m/s. (a) What is the acceleration (magnitude and direction) of the stone while it moves downward, after leaving the person's hand? magnitude     m/s2

A helicopter carrying Dr. Evil takes off with a constant upward acceleration of 7.0 m/s2m/s2. Secret agent Austin Powers jumps on just as the helicopter lifts off the ground. After the two men struggle for 11.0 ss, Powers shuts off the engine and steps out of the helicopter. Assume that the helicopter is in free fall after its engine is shut off, and ignore the effects of air resistance.   What is the maximum height above ground reached by the helicopter?   Powers deploys a jet pack strapped on his back 7.0 ss after leaving the helicopter, and then he has a constant downward acceleration with magnitude 3.0 m/s2m/s2. How far is Powers above the ground when the helicopter crashes into the ground?