Question

Figure 1 shows a man pushing a car with the front brakes are locked and rear wheels are freely to roll. (Note: Use reasonable data and use equilibrium analysis to explain the answer) a) Explain how to find the maximum force this man can exert on the car so that it will not slip. b) Construct the best way in order to prevent the man from slipping. Validate your answer with some of calculation.

Deadline: 21"Mei 2018 EPT 114 STATICS SEM 2 2017/2018 ASSIGNMENT 3 Figure Credis to Gogle Image Figure 1 shows a man pushing a car with the front hrakes are locked and rear wheels are freely to roll. (Note: Use reasonable data and use equilibrium analysis to explain the answer) a) Explain how to find the maximum force this man can exert on the car so that it will not slip b) Construct the best way in order to prevent the man from slipping. Validate your answer with some of calculation Note: You can discuss the assignment and prablem with others but work out on your selutions individually NO COPYING. PENALTY will he given for thove whe are eopy ing.

Answer 1

Draw the free body diagram of the car as shown in the figure. where me is the mass of the car F_A, F_B are friction force on wheels N_A N_B are normal force. p is the force everted by man Draw the force body diagram of the man as show in the figure for car Resolve the force along horizontal direction sigma F_x = 0 F_A + F_0 = pcos theta - (1) resolve the force along \r\n vertical direction sigma F_y = 0 N_A + N_B + psin theta - mg = 0 - (2) Calculate the moment about the point M sigma M = 0 p sin theta times (l_2 + r) + N_A times (l_2) + p cos theta times H - N_A times l_2 = 0 - (3) from equation (1), (2) and (3) we can find out the maximum use of force p which can man expert on the car so that is does not slip \r\n (b) for man Resolve the force along horizontal direction sigma F_y = 0 = > F_m - pcos theta = 0 F_m = - pcos theta - (ii) Resolve the force along vertical direction + sigma F_y