HW11 (Unit 6-Work and Energy) Begin Date: 10/10/2017 12:00:00 AM-Due Date: 10/19
ID: 1779473 • Letter: H
Question
HW11 (Unit 6-Work and Energy) Begin Date: 10/10/2017 12:00:00 AM-Due Date: 10/19/2017 11:59:00 PM End Date: 10/19/2017 11:59:00 PM (1396) Problem 8: A cube of mass m is initially at rest at the highest point of an inclined plane, which has a height of 5.7 m and has an angle of -250 with respect to the horizontal. After being released, you notice it to be moving at v-0.55 m/s a distance d after the end of the inclined plane as shown. The coefficient of kinetic friction between the cube and the plane is = 0.1, and the coefficient of friction on the horizontal surface is r-0.2. initial Final Otheexpertta.com 5096 Part (a) what is the speed of the cube, in meters per second, just after it leaves the inclined plane? Grade Summary Deductions 0% Potential 100% bottom : sin cos0 tan() ||( )-| 7 | 8 | 9 cotan) asin acosO atan acotan) sinh0 cosh0 tanh cotanh0 ·Degrees O Radians Submissions Attempts remaining: 10 0% per attempt) detailed view 123 0 Submit Hint I give up Hints: deduction per hint Hints renaming: 2 Feedback: 0% deduction per feedback 50% Part (b) Find the distance, d, in metersExplanation / Answer
(A) Applying work - energy theorem,
Work done by gravity + work done by friction = change in KE
(m x 9.8 x 5.1) + (- 0.1 x m x 9.8 x cos25 x 5.1/sin25) = m v^2 /2- 0
9.8x 5.1 (1 - 0.214) = v^2 / 2
v = 8.86 m/s .......Ans
(B) Applying work- energy theorem again,
- 0.2 x m x 9.8 x d = m (0.55^2 - 8.86^2) / 2
d = 20 m
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