1. A 16-kg sled is being pulled along the horizontal snow-covered ground by a horizontal force of 24 N. Starting from rest, the sled attains a speed of 2 m/s in 8 m. Find the coefficient of kinetic friction between the runners of the sled and the snow. 2. A dump truck of 2500 kg is being filled with sand. The sand falls straight downward from rest from a height of 2 m above the truck bed, and the mass of sand that hits the truck per second is 55 kg/s. The truck is parked on the platform of a weight scale. By how much does the scale reading exceed the weight of the truck and sand? 3. An 8-g bullet is fired into a 250-g block that is initially at rest at the edge of a smooth table of height 1 m, as shown in the figure. The bullet remains in the block, and after the impact the block lands 2 m from the bottom of the table. Determine the initial speed of the bullet. 4. A 1200-kg car traveling initially with a speed of 25 m/s due east crashes into the rear end of a 9000-kg truck moving in the same direction at 20 m/s. The velocity of the car right after the collision is 18 m/s to the east. How much mechanical energy is lost in the collision? Thanks a lot.