mass - 2 kg 3. A hockey puck slides across rough ice with an initial speed of 12m/s. If it comes to rest after moving 25m, what is the force of friction between the puck and the ice? 4. A box of weight 50N is lifted up 25m in the air by a crane at a constant velocity of 4m/s. a. What is the work done by the crane? b. What is the work done by the Earth? c. What is the initial KE of the object? d. What is the net work done? ge land onjer 5. A force of -100N is applied to a moving object and causes it to slow down from 20m/s to 15m/s. This occurs over a distance of 70m. a. What is the mass of the object? b. What is the acceleration of the object?2. A large sled (weight = 500N) is dragged with a force of 300N through the snow. Assume the friction between the snow and sled is a constant 150N and that the sled travels 80m a. What is the work done by gravity? b. What is the work done by friction? c. What is the work done by the applied force? d. If the sled starts from rest, what is the final speed