2 A kitchen spring scale used to measure the weight of vario

2. A kitchen spring scale used to measure the weight of various foods is designed so that the spring compresses 0.15 in for every 1.2 lbf weight placed on it. Find the mass (lbm) of several tomatoes if the spring deflection is .79 in and the local acceleration of gravity is 31.68 ft/s^2.

Solution

The force applied is obtained by the Hooke\'s formula F = -k x, that is, in this case, it is F = - (0.79/12) (0.15/12) 1.2 = =  -0.0008 = -0.0010. Now, by using the relationship between force, mass, and acceleration, we get the asnwer m = 0.03168