PHY211 General Physics I Ch 8 Worksheet PE and Cons of Energy page 1 of 3 PCC Cascade 1 A 50 kg painter stands on top of a 3 m platform on the roof of a 20 m building a What is the painter s gravitational potential energy with respect to the roof surface b What is the painter s gravitational potential energy with respect to the ground c The painter jumps off the platform onto the rooftop Using the roof as reference what is the kinetic energy of the painter just before he lands on the roof d Using the ground as a reference calculate the kinetic energy of the painter just before he hits the roof 2 An Olympic high diver mass 70 kg stands on a platform 20 m above the surface of the water a What is the diver s gravitational potential energy b The athlete in a then dives into the water If it assumed that all of the diver s potential energy is conserved what is the diver s kinetic energy at the moment just before entering the water c What is the diver s speed just before entering the water d Calculate the instantaneous power generated by the gravitational force just before the diver enters the water e Determine the average power generated by the gravitational force to pull the diver to the earth PHY211 General Physics I Ch 8 Worksheet PE and Cons of Energy page 2 of 3 PCC Cascade 3 A sheep mass 40 kg scampering at 15 m s jumps off the ledge of a cliff 15 m above the ground below a What is the sheep s gravitational potential energy at the top of the cliff Use the ground level below the cliff as reference b What is the sheep s kinetic energy at the top of the cliff 15 m x c Neglecting air drag how much does the sheep s kinetic energy change during its fall just before it impacts the ground below d What is the sheep s speed just before impacting the ground e What is the magnitude and direction of sheep s velocity just before impacting the ground f Calculate the instantaneous power generated by the gravitational force just before the sheep hits the ground g Determine the average time rate of mechanical energy transfer to the sheep during its fateful descent PHY211 General Physics I Ch 8 Worksheet PE and Cons of Energy page 3 of 3 PCC Cascade 4 A mass 2 kg at rest is attached to an ideal spring k 100 N m along the surface of a 40o incline The mass is positioned 1 0 m up the incline from the base of the incline a What is the total mechanical energy of the mass spring system Use the base of the incline as reference b An external applied force pulls the mass 0 2 m down the incline stretching the spring then releases the mass How much mechanical energy does the external applied force transfer to the mass spring system m 1m 40o c What is the difference between the gravitational potential energy Ug for the mass between its initial position and the stretched position just as it is released d What is the difference between the elastic potential energy Uspring for the mass between its initial position and the stretched position just as it is released ro rmax m e What is the total mechanical energy of the mass spring system at the stretched position just as it is released 40o f What is the speed of the mass just as it reaches its initial equilibrium position g If the kinetic friction coefficient between the mass and the incline is 0 2 how fast is the mass traveling when it reaches the initial equilibrium position h Calculate the nonconservative work performed on the mass spring system with friction as the mass travels from its stretched position to the equilibrium position
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