Kim took 5 hours to complete a journey with an average speed of 80km/h. For the first 3 hours, she travelled at an average speed of 60 km/h. What was her average speed for the remaining time of the journey?

You want to move a heavy box with mass 30.0 kg across a carpeted floor. you pull hard on one of the edges of the box at an angle 30∘ above the horizontal with a force of magnitude 240 n, causing the box to move horizontally. the force of friction between the moving box and the floor has magnitude 41.5 n . what is the box's acceleration just after it begins to move