Aparticle travels in a straight line with speed v. the particle slows down and changes direction. the new speed of the particle is v\2 the new velocity has a component of v\4 in the same direction as the initial path of the particle. through which angle has the particle turned? a 27° b 30° c 45° d 60°

Can someone explain to me how to do this problem ?

You have been called to testify as an expert witness in a trial involving a head-on collision. car a weighs 1515 lb and was traveling eastward. car b weighs 1125 lb and was traveling westward at 44.0 mph. the cars locked bumpers and slid eastward with their wheels locked for 22.5 ft before stopping. you have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750 . how fast (in miles per hour) was car a traveling just before the collision? (this problem uses english units because they would be used in a u.s. legal proceeding.)

How does the amount of energy required to hold each proton and neutron in the nucleus compare to the energy released when they are removed?