Learning Goal: You can use this problem for self assessment. Application of Newton's Laws including friction, and Work - KE Theorem Previously you solved the problem "Pull up on an incline with Friction". Now you apply the Work - KE Theorem. A force parallel to the incline surface pulls on a suitcase to make it move up on a rough incline, as shown in 33 With Friction F x It is extremely helpful to make a table like this, fill in each item (use "space holders" for unknown quantities) F x = FNX fx = W = F FNY = = = fy W..= y N +f,+Wy , = ma, F=F+F+fx+W F = F+Fxy+f, +W, Nx Newton's 2nd law F=ma The coefficient of kinetic friction is = 0.63. The suitcase' mass is m = 9.0 kg, The magnitude of the gravitational acceleration is 9.80 m/s. The magnitude of the pulling force F is F = 75.7 N. You can use this problem for self assessment. In addition to the pulling force F there are 3 other forces exerted on the suitcase. Here, the frictional force is kinetic fr. Fill in the table on the right side of the figure Check that the angle in your calculator is in "degrees", sin30 = 0.5 Note: depending on the magnitude of the pulling force F, the suitcase may speed up, slow down or have constant speed. Part A - Calculate the work done by the pulling force F. The displacement is d = 13.4 m up on the incline. Keep 2 digits after the decimal point. Unit is Joules. Work by force F= 1014.53 J Submit Previous Answers Correct Part B - The magnitude of the normal.has been calculated to be 73.97 N. (As self assessment or practice, you should verify this result.) Calculate the work done by the normal force. The displacement is d = 13.4 Im up on the incline. Keep 2 digits after the decimal point. Unit is Joules. Work by normal force = Submit Previous Answers Request Answer Incorrect; Try Again; 4 attempts remaining 0 1 ? J Part C - Calculate the work done by the gravitaional force. The displacement is d = 13.4 m up on the incline. Keep 2 digits after the decimal point. Unit is Joules. Work by gravity = Submit Request Answer ? Part D - The magnitude of the kinetic frictional force.has been calculated to be 46.60 N. (As self assessment or practice, you should verify this result.) Calculate the work done by the kinetic frictional force. The displacement is d = 13.4 m up on the incline. Keep 2 digits after the decimal point. Unit is Joules. Work by kinetic friction = Submit Request Answer ? J J Part E- Calculate the TOTAL work done by all the forces. Keep 2 digits after the decimal point. Unit is Joules. Total Work = Submit Request Answer ] ? = 14.0 m/s. Part F - The suitcase starts with an initital spped of Vi What is its final speed after being pulled up on the incline through a displacement of 13.4 m ? Keep 2 digits after the decimal point. Unit is m/s. Uf = Submit Request Answer m/s Part G - New situation 1: The total work is the same as in Part E. If the Final speed (after being pulled up on the incline through a displacement of 13.4 m) is 8.4 m/s, what was the initial speed? new situation Vi,new = 1 Submit Request Answer ? New situation 2: The pulling force F is changed to an unknown value, but the other three forces remain the same. The initial speed is still v = 14.0 m/s. It is desired to have a new final speed of 14.97 m/s (after being pulled up on the incline through the same displacement of 13.4 m). Part H - New situation 2: What is the New TOTAL work needed to change the speed from still vi = 14.0 m/s to a new final speed of 14.97 m/s? Keep 2 digits after the decimal point. Unit is Joules. NEW New Total situation Work 2 = Submit Request Answer ? m/s Part I - New situation 2: how much work needs to be done by the new pulling force F? Keep 2 digits after the decimal point. Unit is Joules. New situation WorkbyFnew = 2 Submit Request Answer Part J New situation 2: What is the magnitude of the new pulling force F? The up on the incline displacement is still 13.4 m) Keep 2 digits after the decimal point. Unit is Newtons. New situation Fnew = 2 Submit Request Answer ? N ?