Class Management I Help 9HW: Statics and Torque Begin Date: 10/20/2017 11:59:00
ID: 1789969 • Letter: C
Question
Class Management I Help 9HW: Statics and Torque Begin Date: 10/20/2017 11:59:00 PM -- Due Date: 10/27/2017 11:59:00 PM End Date: 11/3/2017 11:59:00 PM (10%) Problem 6: A uniform stationary ladder of length L = 3.4 m and mass M = 14 kg leans against a smooth vertical wall, while its bottom legs rest on a rough horizontal floor. The coefficient of static friction between floor and ladder is = 0.46. The ladder makes an angle = 54° with respect to the floor. A painter of mass 8M stands on the ladder a distance d from its base ©theexpertta.com 33% Part (a) Find the magnitude of the normal force N, in newtons, exerted by the floor on the ladder 33% Part (b) Find an expression for the magnitude of the normal force w exerted by the wall on the ladder. × 33% Part (c) what is the largest distance up the ladder dna , in meters, that the painter can stand without the ladder slipping? Grade Summary Deductions Potential dmax = 1 .541 20% 80% sin 789HOME Submissions Attempts remaining: 2 acosO sinh0 cotan)asin( % per attempt) detailed view acotan0 cosh0 tanh0 cotanh0 Degrees Radians 5% 5% 5% 0 END O BACKSPACE DEL CLEAR Submit Hint give up Hints: 1 for a 5% deduction. Hints remaining: 1 Feedback: 5% deduction per feedback. The ladder does not slip when static friction balances the other forces in the horizontal direction. What other forces are acting horizontally? This will require a carefully constructed free body diagram. Submission History Hints Feedback Totals Answer dmax = 15.54 dmax = 1.346 dmax- 1.54 5% 0% 0% 5% 5% 0% 0% 5% 3 5% -The ladder does not slip when static friction balances the other forces in the horizontal direction. What other forces are acting horizontally? This will require a carefully constructed free body diagram 5% 0% 10% Totals 15% 5% 0% | 20%Explanation / Answer
balancing moment about about the floor point,
M = (3.4/2 x 14 x 9.81 x cos54 ) + ( d x 14 x 8 x 9.81 x cos54) - (3.4 x Nw x sin54) = 0
137.235 + 645.811 d - 2.751 Nw = 0
Nw _max = us N = 0.46 (14 + (8 x 14))(9.81)
= 568.588 N
137.235 + 645.811 d - (2.751 x 568.588) = 0
d = 2.21 m .........Ans