The vehicle land-speed record has long been held by rocket cars. These vehicles resemble the high-speed rocket planes that were used in the early days of the space program, but they have heavy metal wheels. On September 5, 1997, the world land-speed record was set by the British-built Thrust SSC rocket car, which had a top recorded speed of 341 m/s. The kinetic energy of the car at this speed is 5.289 × 10^8 J. What is the car’s mass?

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.