A park ranger driving on a back country road suddenly sees a deer “frozen in the headlights 20.0 m ahead. The ranger, who is driving at 11.4 m/s, immediately applies the
brakes and slows with an acceleration of magnitude 3.80 m/s. How much distance is
required for the ranger's vehicle to come to rest?
Picture the Problem
We choose the positive x direction to be the direction of motion. With this choice it
follows that the initial velocity is v; = +11.4 m/s. In addition, the fact that the ranger's
vehicle is slowing down means that its acceleration points in the opposite direction to the
velocity. Therefore, the vehicle's acceleration is a = -3.80 m/s2. Finally, when the vehicle
comes to rest, its final velocity is zero, ve = 0.

The particle in a two-dimensional well is a useful model for the motion of electrons around the indole ring (3), the conjugated cycle found in the side chain of tryptophan. we may regard indole as a rectangle with sides of length 280 pm and 450 pm, with 10 electrons in the conjugated p system. as in case study 9.1, we assume that in the ground state of the molecule each quantized level is occupied by two electrons. (a) calculate the energy of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels. 9.27 electrons around the porphine ring (4), the conjugated macrocycle that forms the structural basis of the heme group and the chlorophylls. we may treat the group as a circular ring of radius 440 pm, with 20 electrons in the conjugated system moving along the perimeter of the ring. as in exercise 9.26, assume that in the ground state of the molecule quantized each level is occupied by two electrons. (a) calculate the energy and angular momentum of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels.

What occurs during a combustion reaction

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?