| Practice Problem 2-2 (a) |
|
|
Given: A student of weight, W = 120 lb, rides a skateboard with the trucks (wheels) mounted a distance L = 40 in. apart. Assume her feet are positioned inward of the wheels at equal lengths of L/4, and she applies half of her weight at each point. Req'd: What is the Reactant Force, RA [LB]? |
|
|
Solution: If the skateboard is treated as a FBD, the reaction force at A can be gotten by setting the sum of the moments acting at B equal to zero: SMB = (RA)(L) - (W/2)(3L/4) - (W/2)(L/4) = 0 Solving for RA: RA = [(60 LB)(30 in) + (60 LB)(10 in)]/40 in = 60 LB |
|
|
|