A person travels by car from one city to another with different constant speeds between pairs of cities. She drives for 15.0 min at 80.0 km/h, 15.0 min at 50.0 km/h, and 50.0 min at 45.0 km/h and spends 50.0 min eating lunch and buying gas. Determine the average sped for the trip. Determine the difference between the intial citties along the route.

Apassenger walks toward the rear of a moving train. describe her motion as seen from a reference point on the train. then describe it from a reference point on the ground

Consider an ordinary, helium-filled party balloon with a volume of 2.2 ft3. the lifting force on the balloon due to the outside air is the net resultant of the pressure distribution exerted on the exterior surface of the balloon. using this fact, we can derive archimedes’ principle, namely that the upward force on the balloon is equal to the weight of the air displaced by the balloon. assuming that the balloon is at sea level, where the air density is 0.002377 slug/ft3, calculate the maximum weight that can be lifted by the balloon. note: the molecular weight of air is 28.8 and that of helium is 4.

Two steel balls, each of mass m, are welded to a light rod of length l and negligible mass and are initially at rest on a smooth horizontal surface. a horizontal force of magnitude f is suddenly applied to the rod as shown. determine (a) the instantaneous acceleration a of the mass center g and (b) the corresponding rate at which the angular velocity of the assembly about g is changing with time.