A box of mass 4.0 kp is accelerated from rest by a force across a floor at a rate of 2.0 m/s2 for 7.0 s. Find the net work done on the box.

A skier of mass 107 kg travels down a frictionless ski trail. (a) If the top of the trail is a height 186 m above the bottom, what is the work done by gravity on the skier? J (b) Find the velocity of the skier when he reaches the bottom of the ski trail. Assume he starts from rest. m/s

A 2.06 Kg block is pushed 3.31 m along a frictionless horizontal table by a constant 16 N force directed 26.0° below the horizontal, as shown.Determine the work done by the applied force

A 61.8-kg skateboarder starts out with a speed of 1.75 m/s. He does 80.4 J of work on himself by pushing with his feet against the ground. In addition, friction does -221 J of work on him. In both cases, the forces doing the work are non-conservative. The final speed of the skateboarder is 9.19 m/s. (a) Calculate the change (PEF - PEo) in the gravitational potential energy. (b) How much has the vertical height of the skater changed? Give the absolute value. (a) Number (b) Number i Units Units