A 7 kg bowling ball moving to the right at 11 m/s strikes a 5 kg bowling ball moving to the left at 9 m/s. Determine the initial momentum of the system. If the 7 kg bowling ball bounces back with a velocity of 7 m/s, what is the velocity of the 5 kg ball after the collision?

An engineer designs a roller coaster so that a car travels horizontally for 152 ft, then climbs 137 ft at an angle of 34.0° above the horizontal. it then moves 137 ft at an angle of 48.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

Idon’t quite understand this problem

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.