Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

A 1.8 rock is released from rest at the surface of a pond 1.8 deep. As the rock

ID: 1970918 • Letter: A

Question

A 1.8 rock is released from rest at the surface of a pond 1.8 deep. As the rock falls, a constant upward force of 4.3 is exerted on it by water resistance. Let be at the bottom of the pond.


B) Calculate the nonconservative work, , done by water resistance on the rock, the gravitational potential energy of the system, , the kinetic energy of the rock, , and the total mechanical energy of the system, , when the depth of the rock below the water's surface is 0.50 .

C) Calculate the nonconservative work, , done by water resistance on the rock, the gravitational potential energy of the system, , the kinetic energy of the rock, , and the total mechanical energy of the system, , when the depth of the rock below the water's surface is 1.0 .


*I keep getting the kinetic energy incorrect, but close enough so the computer says I have a rounding error.

Explanation / Answer

non conservative work BY WATER RESISTANCE=4.3*(.5) =2.15J work by gravitational potential=1.8*g*.5 =8.82 J kinetic energy=potential energy loss-work done =8.82-2.15 =6.67 J TOTAL MECH ENERGY=ke+pe =6.67 + 1.8*g*(1.8-.5) =29.602 J B) non conservative work BY WATER RESISTANCE=4.3*(1) =4.3J work by gravitational potential=1.8*g*1 =17.64 J kinetic energy=potential energy loss-work done =17.64-4.3 =13.34 J TOTAL MECH ENERGY=ke+pe =13.34 + 1.8*g*(1.8-1) =27.452 J