Please i need help with this problem and please including ex

Please i need help with this problem and please including explanations.The explanation is really important for my understanding.Thanks

I got this below earlier as the solutions but i kind of need explanations for the physics behind it.Please can u help?

>The distance is determinated by the longitudinal speed:

b) Let\'s assume a constant acceleration:

then:

This and the radius r form the legs of a right triangle:

Solution

The principle behind bullet-resistant soft body armor is just basic physics.

\"Performing its function is a two-stage process,\"

Not only does body armor have to stop the projectile that\'s coming at it, it also has to do something with the energy that is pushing it.

One way of explaining this is that soft body armor is essentially a very strong net. Think of a baseball batting cage. The back of the cage is a net formed by many long lengths of tether. The cords of the tether are interlaced with each other and fastened to the cage\'s frame.

When the batter hits the baseball into the cage, the ball has a given amount of energy, in the form of inertia. When the ball hits the net, it pushes back on the tether lines at that given point. The tethers extend from one side of the frame to the other, dispersing the energy from the point of impact over a much wider area. This energy is dispersed further as the tethers are interlaced or, in this case, woven.

When the ball pushes on a horizontal length of the woven tether, that tether pulls on every interlaced vertical tether. These tethers, in turn, pull on all the connected horizontal tethers. The entire net works to absorb the ball\'s inertial energy.

Bullet-resistant material has a similar structure to that of a batting cage net. Long strands of interlaced fiber form a dense net. Of course, bullets travel at much greater speed than a batted baseball. Therefore, the bullet-resistant \"net\" needs to be made from materials of much greater strength.

While one material may be included in the vest primarily as a stopping agent so the projectile does not go any farther, another ballistic material would be included because the way it\'s constructed dissipates the energy throughout the entire panel of the vest,\" says Olsen, \"thus reducing the concentration of energy in one spot. This then reduces the chance of blunt trauma injury, or backface deformation.