Suppose that you can lift no more than 650 N (around 150 lb) unaided. (a) How much can you lift using a 1.4-m-long wheelbarrow that weighs 80.0 N and whose center of gravity is 0.50 m from the center of the wheel (?Fig. E11.16?)? The center of gravity of the load carried in the wheelbarrow is also 0.50 m from the center of the wheel. (b) Where does the force come from to enable you to lift more than 650 N using the wheelbarrow?
Solution 16E Here we shall have to first calculate the mechanical advantage. Mechanical advantage is the ratio of the length of effort arm to that of the load arm. Here, the length of the effort arm is = 1.4 m Length of the load arm is = 0.5 m Therefore, mechanical advantage = 1.4 = 2.8 0.5 The wheelbarrow weigh 80 N. To lift the wheelbarrow, the force needed to be applied is = 80 = 28.6 N 2.8 The remaining force to be lifted unaided = 650 28.6 N = 621.4 N (a) Therefore, the maximum load that be lifted by you is = 621.4 × 2.8 N = 1739.9 N The maximum load that can be lifted using a wheelbarrow is 1739.9 N. (b) The force comes from the normal reaction exerted by the wheelbarrow on the load.
