question 1;
1) Given the following force-displacement graphs, determine the work done in each case. 5.0 4.0 4,0 Force (N) 3.0 2.0 2.0 Force (N) 0 J.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 1.0 20 0 -4.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 Displacement (m) Displacement (m)2) The cable of a large crane applies a force of 2.2 x 10* N to a demolition ball as the ball is lifted vertically a distance of 7.6 m. How much work does this force do on the ball? Is this work positive or negative? Explain.3) Fred is moving into an apartment at the beginning of the school year. Fred weighs 685 N and his belongings weigh 915 N. How much work does the elevator do in lifting Fred and his belongings up five stories (15.2 m)? How much work does the elevator do on Fred on the downward trip?4) A 2.40 x 10' N force, acting at 20" above the surface, is pulling on an 85.8 kg refrigerator across a horizontal floor. The frictional force opposing the motion is 1.67 x 10'N and the refrigerator is moved a distance of 8.00 m. Find the work done by the applied force and the work done by the frictional force.5) A 65.0 kg jogger is running at a speed of 5.30 m/s. What is the jogger's kinetic energy?6) Relative to the ground, what is the energy of a 55.0 kg person at the top of the Sear's Tower in Chicago, which is 443 m high?7) A 75.0 kg skier rides a 2830 m long chair lift to the top of a mountain. The lift makes an angle of 14.6" with the horizontal. What is the change in the skier's potential energy?8) What is the standard unit of power? Is the unit KWh (kilowatt hour) a unit of force, energy or power? Explain.9) What is the power output of a machine which applies a force of 2.50 x 10* N for 12.0 s in pulling a block through 60.0 m?10) A machine has an output power of 10.0 KW. How long would it take for the machine to raise a 5000 kg load through a height of 2.5 m?11) An 80.0 kg box is pushed up a frictionless incline as shown in the diagram. How much work is done on the box in moving it to the top? (Hint, think energy, not forces.) 10.0 m 7.0 m13) In the high jump, the kinetic energy of an athlete is transformed into gravitational potential energy. With what minimum speed must the athlete leave the ground in order to lift his center of mass 2.10 m and cross the bar with a speed of 0.80 m/s?14) If a 4.00 kg board skidding across the floor with an initial speed of 5.50 m/s comes to rest, how much thermal energy is produced?15) A roller coaster is shown in the drawing. Assuming no friction, calculate the speed at points B, C, D, assuming it has a speed of 1.80 m/s at point A. 30 m 25 m 17 m16) A water skier lets go of the tow rope upon leaving the end of a 13.0 m jump ramp at a speed of 14.0 m/s. As the drawing indicates, 14,0 mh the skier has a speed of 13.0 m/s at the highest point of the jump. Ignoring air resistance, determine the skier's height H above the top of the ramp at the highest point.17) The speed of a hockey puck (mass = 100.0 g) decreases from 45.00 m/s to 42.68 m/s in coasting 16.00 m across the ice. a. How much thermal energy was produced? b. What frictional force was acting on the puck?18) A 45.0 kg box initially at rest slides from the top of a 12.5 m long incline. The incline is 5.0 m high at the top. If the box reaches the bottom of the incline at a speed of 5.0 m/s, what is the force of friction on the box along the incline
