Question

The systems shown below are in equilibrium. If the spring scales are calibrated in newtons, what do they read? Ignore the masses of the pulleys and strings and assume the pulleys and the incline are frictionless. (Let m = 2.53 kg and θ = 29.0°.)

a. mg
b. mgcosθ
c. mgsinθ
d. mg/cosθ

Answer 1

In equilibrium, the spring scale reads the tension in the string, which for an inclined plane with angle θ, corresponds to mgcosθ.The correct option is C.

Step-by-step explanation:

Since the system of pulleys and weights is in equilibrium, the reading on the spring scales represents the tension in the string that is equal to the component of the gravitational force, represented by w = mg, acting along the string's direction. Considering the angle θ = 29.0° and assuming we ignore any friction and pulleys' masses, the tension along the string on an inclined plane will be mgcosθ because this is the force component parallel to the plane that is being balanced by the tension in the string.